Claimant, William Neufeld appeals from an order of the Industrial Commission denying his claim for worker’s compensation benefits. Neufeld began working for Browning Ferris Industries (BFI) in June 1978 as a garbage collector. Neufeld alleges that in May or June of 1982, he injured his back in the course of his employment with BFI. He testified that while lifting a heavy steel garbage can he noticed a strain or pull in his lower left hip area. He continued working and did not notify anyone of the alleged accident.
Neufeld testified that he did not notify BFI of his injury because he felt it was only a strained muscle which would heal itself without treatment. He also testified that a memorandum posted on the drivers’ board at BFI regarding absenteeism reinforced his “supposition that minor strains and stuff weren’t that important to worry about.” The memorandum read as follows:
“As you all know, it is vacation season again. Lately, though, we have had a distressingly poor absenteeism record. As of now, we were able to allow two employees off for vacation at one time, but should the absenteeism continue, that may not be possible from the standpoint of keeping the costs at work force in effect. I urge you all to help out, unless you are seriously ill, to attempt coming to work. Minor aches and pains are occasionally a result of our work, unless they are a chronic problem, should be expected.”
Neufeld continued to work and perform his usual duties following the alleged accident. He saw Dr. Rae, a chiropractor, on June 11, 1982, complaining of a slight muscle strain in his lower back. He again saw Dr. Rae on August 10, 1982. Dr. Rae testified that Neufeld indicated on that date that he had injured his back lifting garbage cans and that his back had been bothering him for a couple of months. Dr. Rae testified that he did not file a report with the Industrial Commission because Neufeld thought it was only a slight strain which would just go away.
Neufeld testified that his back problems worsened in September of 1982. He saw Dr. Rae on October 20 and again on November 15 and 19. Following the Novem*901ber 19 appointment, he began seeing Dr. Rae approximately twice a week.
Neufeld testified that he first notified BFI’s safety manager, Jim Robinson, of his injury in mid-September of 1982. He stated that he told Robinson he had hurt his back in May and that it was still bothering him. He further testified that he spoke to Robinson a second time in November, telling him that he was going to have X-rays, and a third time in December.
Robinson was no longer employed at BFI at the time of the hearing and did not testify. The parties stipulated that Robinson would have testified that Neufeld first notified him of his back problems on December 14, 1982. Robinson wrote a memorandum concerning the December 14 conversation which was placed in Neufeld’s personnel file. The memo provided as follows:
“Subject: Bill Neufeld's Back Problem “Talked to Bill today about his back problem. He indicated he did not know how it had happened, or when it happened. He thought he had done it at home but was not sure. He was filing all claims under company insurance.”
On December 9, 1982, Neufeld asked BFFs dispatcher, Joe Petera, for two days off to help relieve his back pain. Neufeld did not inform Petera that his back problems were work-related. At BFFs annual Christmas party, on the evening of December 17, 1982, Neufeld spoke to Petera and to John Weber, BFFs Operations Manager, about his back problem. They testified that Neufeld told them the injury might have occurred at home.
Neufeld’s back problems continued to escalate and on January 5, 1983, he took some time off work. At the request of John Weber, Neufeld saw Dr. Daines, an orthopedic surgeon, on January 11. Neufeld gave Dr. Daines a history of his back problems stating that they began in April or May of 1982. He did not give a specific date of accident, but did indicate that his symptoms worsened when he was performing his job duties. Dr. Daines felt that Neufeld probably had a herniated disk and advised him stop working and to stay m bed.
In the meantime, Neufeld had continued to see Dr. Rae. On February 17, 1983, Dr. Rae referred him to Dr. O’Brien. Dr. O’Brien diagnosed Neufeld as suffering from a herniated disk and sent him to a neurological surgeon. Dr. O’Brien testified that based on the history Neufeld provided him, it was his opinion that Neufeld’s injury resulted from lifting garbage cans.
Neufeld underwent surgery on February 21, 1983. He returned to work part-time on April 19, 1983, doing light-duty yard work. Because BFFs company physician and Neufeld’s treating physicians agreed that he should not return to garbage collection, he left BFI on May 18, 1983. Dr. O’Brien testified that following surgery Neufeld had a permanent partial impairment rating of 20% of the whole man. Dr. Daines rated Neufeld’s impairment at 7.5% of the whole man.
Neufeld turned in an insurance claim on BFFs group health policy seeking coverage for the injury on February 7, 1983. Dr. Rae had previously filed under the same policy to obtain payment for his treatment of Neufeld from June through December of 1982. On the claim, Neufeld indicated that the accident or sickness began in May of 1982, that it was a strained back, and that he did not know when or how it occurred. In answer to the question of whether the injury was due, in any way, to the patient’s occupation, he checked “no” and wrote “unknown.” He also indicated that he would not be filing for worker’s compensation.
Neufeld filed for worker’s compensation benefits on February 22, 1983. Hearings were held on October 25, 1983 and on November 9, 1983. The commission ultimately denied Neufeld’s claim concluding (1) that he had not suffered a compensable accident within the meaning of the worker’s compensation law, and (2) that his claim was barred due to delay of notice. Neufeld then moved for reconsideration. The commission denied the motion stating *902that Neufeld had failed to prove that his back injury was the result of an accident as defined by the Idaho Worker’s Compensation Law. This appeal followed.
On appeal, Neufeld asserts that the commission erred in finding that he failed to establish a compensable injury. He further asserts that BPI was not prejudiced by his delay in giving notice of his injury, and therefore, that the commission erred in finding that his claim was barred due to the delayed notice. Because we affirm the commission’s finding that Neufeld did not establish that he had suffered an accident within the meaning of the worker’s compensation law, we find it unnecessary to address the notice issue.
Before reviewing the evidence that the commission relied on in reaching its decision, we note the limited scope of our review. In appeals from the Industrial Commission our review is necessarily limited to determining whether the commission’s factual findings are supported by substantial and competent evidence. ID. CONST. art. 5, § 9; I.C. § 72-732; Wolf v. Kaufman & Broad Home Systems, 106 Idaho 838, 683 P.2d 874 (1984). The determination of whether a particular injury arose out of and in the course of employment is a question of fact for the commission. Teffer v. Twin Falls School Dist. No. 411, 102 Idaho 439, 631 P.2d 610 (1981). Such a determination necessarily involves weighing the evidence and assessing the credibility of the various witnesses, and is therefore committed to the expertise of the commission. The commission’s conclusions as to the weight and credibility of the evidence will not be disturbed on appeal unless they are clearly erroneous. Houser v. Southern Idaho Pipe & Steel, Inc., 103 Idaho 441, 649 P.2d 1197 (1982).
With this standard in mind, we review the evidence to determine whether the commission’s finding that Neufeld did not establish a compensable injury is supported by the record. A claimant in a worker’s compensation case has the burden of proving that he is entitled to benefits. The claimant must prove not only that he was injured, but also that his injury was the result of an accident arising out of and in the course of his employment. His proof must establish a probable not merely a possible connection between cause and effect to support his contention that he suffered an accident. Dean v. Dravo Corporation, 95 Idaho 558, 561, 511 P.2d 1334, 1337 (1973).
In the instant case, the commission determined that Neufeld had failed to meet this burden. Specifically, the commission found that Neufeld had not established that he suffered an accident within the meaning of the worker’s compensation statutes. I.C. § 72-102(14) defines “injury” as a personal injury caused by an accident arising out of and in the course of employment. An “accident” is defined as “an unexpected, undesigned, and unlooked for mishap, or untoward event, connected with the industry in which it occurs, and which can be reasonably located as to time when and place where it occurred, causing an injury.” I.C. § 72-102(14)(b). Our prior cases, paralleling this definition, indicate that an accident occurs when, in the course of employment, any “unexpected, undesigned, unlooked-for or untoward event or mishap” occurs. See, e.g., Wynn v. J.R. Simplot Co., 105 Idaho 102, 105, 666 P.2d 629, 632 (1983).
Neufeld’s testimony indicates that he does not know exactly when or where the alleged accident occurred. He testified that sometime in May or June of 1982 he was lifting a steel garbage can and noticed a strain or pull in his lower back. He did not report the incident, and continued his usual work in the months following its occurrence. It is uncontradicted that Neufeld first reported the accident at least three months after it allegedly occurred. Neufeld testified that he reported it in mid-September while Robinson’s stipulated testimony indicates that it was not reported until December.
Neufeld asserted that he did not report the injury because he felt it was only a pulled muscle which would heal it*903self without medical attention. He contends that his decision not to report the injury was influenced by a company memorandum on absenteeism, the text of which was set out above. However, the memorandum in question addressed only the problem of absenteeism. It contained nothing to suggest that employees should not report on-the-job injuries. In fact, BFI’s policy manual specifically provided that all accidents were to be promptly reported and that a failure to report an accident was cause for immediate discharge.
“Any accident or injury, no matter how minor it may appear, must be reported promptly to your Supervisor. Failure to do so could jeopardize the company’s legal position. Because of this, the failure to promptly report an accident or injury is considered one of the most serious offenses against company policy and can result in immediate termination of employment.”
Neufeld admitted that he had read the manual several times and that he was familiar with the above-quoted provision.
In addition, the record reflects that Neufeld had filed three previous worker’s compensation claims during the course of his employment at BFI. All three of the previous injuries were reported to the employer on the day they occurred.
The record also reflects that Neufeld indicated to three of the supervisory personnel at BFI that his back injury might have occurred at home, rather than in the course of his employment. The memorandum prepared by Jim Robinson following his December 14,1982, conversation with Neufeld states that Neufeld represented that the injury might have happened at home and that Neufeld was filing for benefits under BFI’s group health insurance policy. Neufeld did, in fact, file for health care benefits for the injury pursuant to the policy. He indicated on the claim form that his injury was not caused by an industrial accident and that he would not be filing for worker’s compensation.
Based on our review of the record, the evidence, although conflicting, was sufficient to support the commission’s finding that Neufeld failed to establish that he had suffered a compensable injury. Accordingly, the decision of the Industrial Commission is affirmed.
Costs to respondent.
No attorney fees on appeal.
SHEPARD, BAKES and HUNTLEY, JJ„ concur.