OPINION OF THE COURT
RENDELL, Circuit Judge.Appellant The Okonite Company (“Ok-onite”) appeals from the order of the District Court granting summary judgment in favor of appellee Local 1992 of the International Brotherhood of Electrical Workers (“Local 1992”) on appellee’s claim that appellant violated the Worker Adjustment and Retraining Notification Act (“WARN Act”), 29 U.S.C. §§ 2101-09, by failing to give its employees sufficient advance notice of a plant closing. The District Court held that any waiver of these claims in exchange for severance benefits was invalid for lack of consideration, because appel-lee union members had been entitled to such benefits without executing the waiver, under the unambiguous terms of their severance agreement. We find that the District Court erred in holding that the severance agreement was unambiguous, and will reverse and remand for further proceedings consistent with this opinion.
I.
Appellant Okonite is a manufacturer and seller of high voltage wire and cable. In January 1995, Okonite employed 209 employees at its North Brunswick, New Jersey facility, 160 of whom were represented by appellee Local 1992. As demand for its product decreased, Okonite was forced to lay off a substantial number of employees between January 1995 and May 1996. Ok-onite’s economic problems persisted, and in June 1996, it decided it could no longer continue production at the North Brunswick facility. Okonite announced its intention to close the North Brunswick facility on July 8, 1996, and twenty-one employees were laid off effective that date. Over the next nine months, the remaining employees were laid off, 1 and the plant was closed on March 31,1997.
The employees’ entitlement to benefits after the plant was closed was governed by the severance agreement contained in the collective bargaining agreement between Local 1992 and Okonite. All but one of the employees elected severance payments; he was laid off with a right of recall or transfer to another Okonite facility through May 17, 2001. The vast majority of those who elected severance pay had fifteen or more years of service with Okon-ite, and therefore received between thirteen and seventy-eight weeks of severance pay. Employees who chose to receive severance benefits were required to execute a severance computation form that provided:
I understand that by accepting severance pay I will be deemed to have waived all my rights as an employee, excluding only those rights or benefits to which I may have become entitled to under any Pension, Welfare or other benefit program established by the Company which I may have been eligible to participate in.
On July 11, 1996, Local 1992 filed a grievance against Okonite, alleging that Okonite had violated the collective bargaining agreement by terminating employees without prior notice. Okonite denied the griev-*341anee, and Local 1992 filed the instant suit in the District Court, alleging that Okonite had violated the WARN Act by failing to provide sixty days advance notice to employees laid off when the plant closed on July 8,1996, and by failing to provide sixty days advance notice to employees laid off during “mass layoffs” between January 1, 1995 and July 8, 1996. The District Court granted Okonite’s motion to dismiss the latter allegation, finding that, during the relevant time period, there had not been any “mass layoffs” that required advance notice. This determination has not been challenged on appeal.
The District Court also found that ap-pellee had not waived its first claim, in spite of the waiver language in the severance computation form. The Court determined that the employees had not received any enhanced benefit in exchange for agreeing to waive their rights, because, under the unambiguous terms of the severance agreement, the employees were already entitled to the severance benefits they received in exchange for signing the severance computation form. The Court noted:
“By signing the Severance Form, the Bargaining Unit Employees received nothing other than that to which they were already entitled. Accordingly, valid consideration does not exist to support the release language of the Severance Form.”
The District Court then granted summary judgment in favor of appellee on this claim, finding that the employees who had been laid off beginning July 8, 1996 and ending September 6, 1996 had not received the requisite WARN notice, and were therefore entitled to sue for damages. The Court also denied appellee’s request for prejudgment interest, and granted its request for attorney’s fees. Appellant filed the instant appeal. We exercise our appellate jurisdiction pursuant to 28 U.S.C. § 1291. The District Court had jurisdiction based on 28 U.S.C. § 1381 and 29 U.S.C. § 2104(a)(5).
II.
The District Court’s summary judgment ruling was based on its determination that the terms of the severance agreement were unambiguous, and entitled appellee union members to severance benefits prior to signing the waiver form, thereby rendering such waiver invalid for lack of consideration. The question of whether contract terms are clear or ambiguous is a legal one subject to plenary review. See Pennbarr Corp. v. Insurance Co. of N. Am., 976 F.2d 145, 149 (3d Cir.1992). We will affirm a grant of summary judgment on an issue of contract interpretation only if we conclude that the contractual language is subject to only one reasonable interpretation. See Tamarind Resort Assocs. v. Government of the Virgin Islands, 138 F.3d 107, 110-11 (3d Cir.1998); Sumitomo Mach. Corp. of Am., Inc. v. AlliedSignal, Inc., 81 F.3d 328, 332 (3d Cir.1996); Pennbarr Corp., 976 F.2d at 149.
We turn first to the language of the severance agreement in order to determine if the District Court properly held that it was unambiguous. The portions most relevant to our analysis are paragraphs two, three, and four:
2. Employees will be eligible for severance pay as herein provided if they are involuntarily terminated as the result of a permanent transfer of machinery, equipment, or operations to other plants of the Company, due to the permanent cessation of such work at the North Brunswick Plant or in the event of a total plant shutdown.
3. An employee involuntarily terminated and eligible for severance pay in accordance with the foregoing shall, within the time limits herein established, elect one of the following options:
(a) Layoff with such recall rights as he may be entitled to under the collective bargaining agreement then in existence between the parties.
*342(b) Severance pay in accordance with the foregoing, in which case such employee will be deemed to have waived all of his rights as an employee, excluding any rights or benefits to which he may have become entitled under any Pension, Welfare, or other benefit program established by the Company in which he may have been eligible to participate. In the event such employee is rehired at a later date by the Company, he shall be rehired as a new employee.
(c) The time, measured from the date of termination of employment, within which an employee may make such election shall be as follows:
Completion of Time Within to Full Years of Work Make Election
5 One (1) Month
10 Two (2) Months
15 Three (3) Months
20 Four (4) Months
Any employee failing to notify the Company of his election within the time limits established herein shall be deemed to have elected in favor of the first option referred to above — layoff with retention of recall rights.
4. In the event of a total plant shutdown, employees who are laid off at the time of such shutdown, or who have as of the date of such shutdown been laid off within six (6) months prior to the date of the announcement of a total plant shutdown, and who retain recall rights under the collective bargaining agreement shall be deemed to have been involuntarily terminated as the result of such plant shutdown and shall be entitled to severance pay.
App. 102-03. The District Court examined these provisions and concluded that, under the plain meaning of the agreement, employees who were involuntarily terminated as a result of a total plant shutdown were automatically entitled to severance pay under paragraph four, and were not required to proceed under paragraph three, which would have required them to elect either severance pay or recall rights, and waive their rights as employees if they chose severance pay. In interpreting these provisions, the District Court noted that the severance agreement did not explicitly provide that paragraph three did not apply to total plant shutdowns, and when read in isolation, paragraph three could be read as applying to both partial and total plant closings. Nonetheless, the Court concluded, when paragraph three was read in conjunction with paragraph four, which was explicitly limited to total plant shutdowns, it was clear that paragraph three applied only if there was a partial plant closing, and not if there was a total plant shutdown.
The District Court also concluded that the language in paragraph four that employees “shall be entitled” to severance pay indicated that employees’ eligibility for severance pay after a total plant shutdown was not conditioned on a waiver of their rights. Thus, appellee union members, as employees involuntarily terminated as a result of a total plant shutdown, were entitled to severance benefits under paragraph four of the agreement, and any waiver of their rights in exchange for these benefits they were already entitled to was void for lack of consideration. See Williams v. Phillips Petroleum Co., 23 F.3d 930, 935-36 (5th Cir.1994) (requiring adequate consideration for release of a WARN Act claim); see also Ponzoni v. Kraft General Foods, Inc., 774 F.Supp. 299, 313 (D.N.J.1991) (requiring consideration for release of claims); Mullen v. New Jersey Steel Corp., 733 F.Supp. 1534, 1545-46 (D.N.J.1990) (holding that plaintiffs receipt of benefits he was not otherwise entitled to, in exchange for release of claims, was consideration for release). The District Court also noted that its interpretation of the severance agreement was “further supported by the absence of any conflicting extrinsic evidence.”
Both parties contend on appeal that the agreement is unambiguous, but offer conflicting interpretations. Appellee advocates the District Court’s interpretation, *343arguing that the only reasonable interpretation of the agreement is that appellee union members’ entitlement to severance benefits under paragraph four was not conditioned on a waiver of their rights, and that the waiver was therefore ineffective because there was no consideration to support it. Appellant proposes an alternative interpretation, arguing that the District Court erred in holding that paragraph three of the severance agreement applied only to partial plant closings, and that, when paragraphs two and three are read together, it is clear that paragraph three also applies to total plant closings so that a waiver of other claims is a condition to severance.2 Paragraph four, appellant urges, was not intended to provide unconditional entitlement to severance benefits in the event of a total plant shutdown, but, instead, to enlarge the class of employees eligible for severance pay under paragraph three to include employees who were laid off at the time of the total plant shutdown, or who were laid off within the six-month period prior to the announcement of the total plant shutdown. The language in paragraph four providing that employees will be “entitled” to severance pay, appellant contends, can be interpreted as meaning that these additional employees will be “eligible” to receive severance pay if they agree to the terms provided in paragraph three, i.e., if they choose severance pay, they must waive their rights as employees. Furthermore, appellant notes, the choice provided in paragraph three is not meaningless in the context of total plant shutdowns; although employees obviously could not be recalled to the plant that is shut down, they do retain rights to be transferred to another Okonite facility.3 In fact, as appellant notes, one employee who did not timely submit his election to receive severance pay was placed on layoff status and given a right of recall through May 17, 2001 via intra-company transfer, in accordance with paragraph three.
We believe that the District Court erred in holding that its interpretation of the severance agreement was the only reasonable one, and we find that appellant’s interpretation of the agreement is equally plausible. In determining whether contractual language is ambiguous, courts should consider the contract language, the proffers of the parties, and the extrinsic evidence offered in support of each interpretation. See In re New Valley Corp., 89 F.3d 143, 150 (3d Cir.1996). The District Court relied primarily on the language of the severance agreement in making its determination, finding that the explicit language of paragraph four trumped paragraph three, and focusing on its view (as well as the dictionary’s) of the definition of “entitle” in paragraph four. The District Court did not refer to any basis in the record for its conclusion, other than noting that there was no extrinsic evidence contrary to its interpretation, and listing the materials it reviewed in making its determination in a footnote at the beginning of its opinion. App. 471-72 n. 3. We do not believe that the meaning of the language in the agreement is as clear as the District Court concluded, and find that additional factors should be considered in interpreting its terms.4
First, the District Court determined that paragraph four, and not paragraph three, applies to total plant shutdowns, *344because paragraph four, and not paragraph three, specifically references total plant shutdowns. However, the introductory language to paragraph three can reasonably be interpreted in a way that casts doubt on its conclusion that the provision clearly does not apply to total plant shutdowns. Paragraph three applies to employees “involuntarily terminated and eligible for severance pay in accordance with the foregoing.” The “foregoing” refers to paragraph two, which reads:
Employees will be eligible for severance pay as herein provided if they are involuntarily terminated as the result of a permanent transfer of machinery, equipment, or operations to other plants of the Company, due to the permanent cessation of such work at the North Brunswick Plant or in the event of a total plant shutdown.
App. 102-03 (emphasis added). Therefore, paragraph three appears to include a total plant shutdown as one of the “foregoing” events, suggesting that paragraph three would apply in such a situation.
Second, the District Court held that the use of the word “entitle” in paragraph four signified an absolute right to severance benefits in the event of a total plant shutdown, rather than the right to elect benefits in exchange for the waiver of rights provided for in paragraph three. Paragraph four reads:
In the event of a total plant shutdown, employees who are laid off at the time of such shutdown, or who have as of the date of such shutdown been laid off within six (6) months prior to the date of the announcement of a total plant shutdown, and who retain recall rights under the collective bargaining agreement shall be deemed to have been involuntarily terminated as the result of such plant shutdown and shall be entitled to severance pay.
App. 103 (emphasis added). -Paragraph four can just as easily be read as defining who “shall be deemed to have been involuntarily terminated as the result of such plant shutdown” and therefore “entitled” to elect severance under paragraph three. It could be said that the purpose of paragraph four is to enlarge the class of employees eligible to choose under paragraph three, not only to those who are laid off at the time of the total plant shutdown, but also to those who were laid off within the six previous months (some of whom may have previously made a different election under paragraph three). Further, the use of the word “entitle” does not necessarily mean that the employees provided for under paragraph four would be entitled to severance without giving whatever waivers might be required; it can be interpreted to mean that, having previously exercised an option for layoff with recall rights, they are entitled to the opportunity, once the plant has been totally shut down, to choose again, under paragraph three. Appellant has made a plausible argument that this provision is intended to prevent an employer from avoiding severance obligations by effectively laying off most employees over several months, then shutting down with a skeleton crew.
It could also be important in determining the meaning of paragraph three to consider whether the recall option provided by its terms has meaning in the event of a total plant shutdown, in light of the agreement providing for intra-company transfer upon total plant shutdown. Are these transfer rights commensurate with the recall rights of paragraph three? We do not know whether the District Court considered this factor, or any other factors as to the practical effect or implementation of these provisions, in evaluating the agreement. If it did, it is not apparent on the face of its ruling, which, as we note above, relies solely on the language of the agreement.
Because the severance agreement is susceptible of two reasonable interpretations, the District Court erred in holding that the agreement clearly and unambiguously provided that appellee union members were entitled to severance benefits without *345the requirement that they waive all claims, and in determining, as a result, that the waivers were invalid for lack of consideration. Accordingly, we will reverse the grant of summary judgment and remand for further proceedings in light of this opinion.
. Additionally, between January 1, 1995 and March 31, 1997, 19 employees were transferred to other plants, 16 retired, one was terminated for cause, one voluntarily quit, and one passed away.
. We note that, although our dissenting colleague discusses the breadth of the waiver itself, we do not address that issue, as the District Court did not reach that issue and the parties did not argue it on this appeal.
. The agreement regarding intra-company transfer provides in relevant part: "The Company agrees that any employee who has been involuntarily terminated as a result of a Plant shutdown and who notifies the Company that he or she is available for employment at any of the Plants set forth herein, shall be given first consideration for any job opening.” App. 96.
.We note that the District Court is not prevented from entering summary judgment on remand if it relied upon, although it did not refer to, persuasive evidence establishing that its interpretation was the only reasonable one.