Opinion by
Mr. Justice Bell,Plaintiff, a teacher duly certified and qualified to teach in our public schools, was appointed by the defendant School Board to teach as a “substitute teacher” during the school year 1947-48 and the school year 1948-49. The appointment was so recorded in the minutes of the School Board. Pursuant to this appointment the plaintiff taught the fourth grade, replacing Miss Gwenn Leyshon, a regular teacher, i.e., “a regular professional employe.”
Plaintiff was also employed by defendants during each of the next three years, viz., 1949-50, 1950-51 and 1951-52. In each of these years the minutes of the School Board described the plaintiff as “a teacher” rather than “a substitute teacher” as they had in the first two years of her employment.
On March 13, 1952 defendant Hetra, Superintendent of Schools, notified the plaintiff by letter that the state legislature by the Act of January 14, 1952, P.L. 2018, 24 PS §25-2518, had amended the Public School Code Act of March 10, 1949, P.L. 30, 24 PS, supra, to provide penalties in cases where a school district employs substitute teachers to fill a vacancy which exists for a full year or more. The letter added that “all teachers on a substitute basis who have one year agreements, may or may not have these agreements renewed next year.” The plaintiff was not appointed for the year 1952-53. Plaintiff, contending she became a temporary professional employe in 1949 and was entitled to tenure, commenced this action in mandamus on July *56314, 1953. The Court below sustained defendants’ preliminary objections and dismissed the complaint.
The pertinent provisions of the Public School Code of 1949, supra, are:
“Section 1101. Definitions. — As used in this article,
“(1) The term ‘professional employe’ shall include teachers, supervisors, supervising principals, principals, directors of vocational education, dental hygienists, visiting teachers, school secretaries the selection of whom is on the basis of merit as determined by eligibility lists, school nurses who are certified as teachers and any regular full-time employe of a school district who is duly certified as a teacher.
“(2) The term ‘substitute’ shall mean any individual who has been employed to perform the duties of a regular professional employe * during such period of time as the regular professional employe is absent on sabbatical leave or for other legal cause authorized and approved by the board of school directors or to perform the duties of a temporary professional employe who is absent.
“(3) The term ‘temporary professional employe’ shall mean any individual who has been employed to perform, for a limited time, the duties of a newly created position or of a regular professional employe whose services have been terminated by death, resignation, suspension or removal.
“Section 1108. Temporary Professional Employes.— It shall be the duty of the county superintendent of schools or the district superintendent, as the case may be, to notify each temporary professional employe, at least twice each year during the period of his or her employment, of the professional quality, professional *564progress, and rating of his or her services. No temporary professional employe shall be dismissed unless rated unsatisfactory, and notification, in writing, of such unsatisfactory rating shall have been furnished the employe within ten (10) days following the date of such rating. A temporary professional employe whose work has been certified by the county superintendent of schools or the district superintendent to the secretary Of the school district, during the last four (4) months of the second year of such service, as being satisfactory shall thereafter be a ‘professional employe’ within the meaning of this article. The attainment of this status shall be recorded in the records of the board and written notification thereof shall be sent also to the employe. The employe shall then be tendered forthwith a regular contract of employment as provided for professional employes. No professional employe who has attained tenure status in any school district of this Commonwealth shall thereafter be required to serve as a temporary professional employe before being tendered such a contract when employed by any other school district.
“Any temporary professional employe who is not tendered a regular contract of employment at the end of two years of service, rendered as herein provided, shall be given a written statement signed by the president and secretary of the board of school directors and setting forth explicitly the reason for such refusal.
“Temporary professional employes shall for all purposes, except tenure status, be viewed in law as full-time employes, and shall enjoy all the rights and privileges of regular full-time employes.”
The basic contention of plaintiff is that her services as a school teacher cannot be terminated because under the Code she was a “temporary professional employe” from 1949 through 1952 and hence entitled to “profes*565sional employe” status with its attendant tenure protection. The Board on the other hand insists that the plaintiff accepted each appointment as a substitute teacher in which case tenure status would never attach.
The School Board also contends (1) that since plaintiff’s work had not been certified by the Superintendent as being satisfactory in accordance with the School Code, she could not attain the status of a “professional employe”; and (2) that she was entitled to the status of “professional employe” at the end of her second year, if ever, and since she made no claim to such status for more than two years she is barred by laches. The plaintiff contends that by failing to rate her work unsatisfactory during the course of her employment, the Superintendent waived his right to so rate her now. Therefore, she prayed (1) that the defendant Superintendent be commanded to rate her work satisfactory; (2) that the School Board be required to tender her a written contract as provided for “professional employes”; (3) that she be assigned regular teaching duties; and (4) that she be reimbursed for loss of salary.
We agree with the lower Court that mandamus should not be issued in this case. Miss Leyshon was employed by defendant School Board as “A regular professional employe” (teacher) prior to 1949. Neither the complaint nor the record is clear as to why she was absent thereafter, or whether her services were terminated by death or resignation or suspension or removal, or whether she was absent for legal cause authorized and approved by the Board of School Directors. An averment and proof of such facts would be indispensable if the case were to be . decided on its merits. The reason is obvious from the Code which delineates in letail the difference between a substitute *566teacher and a temporary professional (employe) teacher.
But even if it be assumed arguendo that plaintiff clearly averred that the services of Miss Leyshon, a regular teacher (whose place plaintiff took) had been permanently terminated by resignation or removal, plaintiff would not be entitled to the relief she seeks for two reasons, the first of which is that we cannot compel (as plaintiff requests) the Superintendent to give the plaintiff a satisfactory rating.
The law is clear that mandamus lies only when there is a clear legal right in the plaintiff and a corresponding duty in the defendant and only where the act requested is ministerial and not discretionary: Travis v. Teter, 370 Pa. 326, 87 A. 2d 177; Commonwealth ex rel. McLaughlin v. Erie County, 375 Pa. 344, 100 A. 2d 601. Cf. Kendall v. United States, 12 Peters 524, 9 L. Ed. 1181.
In Travis v. Teter, 370 Pa., supra, this Court said (page 330) : “[Mandamus] is not a matter of right but in certain circumstances is a matter for the sound discretion of the court: Waters v. Samuel, 367 Pa. 618, 80 A. 2d 848. It is well settled that in a mandamus proceeding a Court can compel a public official who is vested with a discretionary power to exercise that discretion; but (unless the discretion is arbitrarily or fraudulently exercised or is based upon a mistaken view of the law) it cannot interfere with or control the official’s discretion or judgment. Expressed another way, it is the discretion and judgment of the official (who is vested with a discretionary power) which prevails and not that of a Court or a jury or a person aggrieved; and a Court cannot compel such official to exercise his discretion in a manner which will produce a result which the Court may deem wise or desirable: Kaufman Construction Co. v. Holcomb, 357 Pa. 514, *56755 A. 2d 534; Tenenbaum v. D’Ascenzo, 356 Pa. 260, 51 A. 2d 757; Anderson v. Philadelphia, 348 Pa. 583, 36 A. 2d 442; Souder v. Philadelphia, 305 Pa. 1, 156 A. 245.”
Plaintiff recognizes these principles but argues that they have no applicability in the instant case because failure of the Superintendent to rate her work unsatisfactory now makes rating her “satisfactory” a ministerial act. We do not agree with this contention. The Public School Code of 1949 * states, inter alia, that those “temporary professional employes” whose work is certified as satisfactory shall thereafter be “professional employes” and thus entitled to a regular contract of employment. It does not say that “professional employe” status shall accrue to those whom the Superintendent fails to rate unsatisfactory.
Article XI, §1108 of the Code provides as follows: “It shall be the duty of the county superintendent of schools or the district superintendent, as the case may be, to notify each temporary professional employe, at least twice each year during the period of his or her employment, of the professional quality, professional progress, and rating of his or her services. No temporary professional employe shall be dismissed unless rated unsatisfactory, and notification, in writing, of such unsatisfactory rating shall have been furnished the employe within ten (10) days following the date of such rating. A temporary professional employe whose work has been certified by the county superintendent of schools or the district superintendent to the secretary of the school district, during the last four (4) months of the second year of such service, as being satisfactory shall thereafter be a ‘professional employe’ within the meaning of this article.”
*568It is clear from the Code that even if plaintiff were a temporary professional employe, she could not become a professional employe within the meaning of Article XI of the Code unless and until her work had been certified by the superintendent as satisfactory.
If plaintiff believed she was entitled to the status of a temporary professional employe in 1949-50 and in 1950-51 and during that period should have been rated by the superintendent “satisfactory” “at least twice each year”, and that during or at the expiration of the last four months of the second year of such service she was entitled to a rating of a “professional employe”, she should have promptly demanded the rights which appertained to her at that time and not waited until July, 1953. As Mr. Justice (now Chief Justice) Horace Stern said in Ralston v. Derry Township School District, 363 Pa. 58, 69 A. 2d 69, at page 62: “But after the passage of the Act of 1939 he could not acquire tenure status except by meeting the conditions prescribed therein, which included the certification by the county or district superintendent, during the second year of his service, that the quality of his work was satisfactory.”
Therefore, plaintiff is not entitled to mandamus because of her laches. It would certainly be difficult and might be impossible for a superintendent in July, 1953, to recall how plaintiff should have been rated twice in 1949 and in 1950 and in other years. If school teachers could, years after they might have been entitled to a higher rating as a teacher or years after another teacher had been employed in their place, successfully claim the status of a temporary professional employe or of a professional employe, it would create budgetary and debt difficulties for school districts which would certainly be contrary to the public interest.
*569The Order of the Court below is affirmed; costs to be paid by appellant.
Italics throughout, ours.
March 10, 1949, Art. XI, §1108, 24 PS §11-1108.