Decision making and decision changes were studied in late adolescents regarding post-high school choices. A branching questionnaire was constructed and mailed to 1239 late adolescents who during the preceding year had indicated on the American College Test (ACT) that Utah State University (USU) was their first choice for college attendance, but whose names did not appear on the USU Registrar's list of enrolled freshmen, Fall 1969. 62% of the questionnaires were returned. Questions were asked concerning post-high school decision making and decision change: What alternatives to attendance at USU were chosen? Was the alternative chosen college-related or was the change made to a non-college alternative? Who most influenced the decision to change alternatives? Was the change of decision permanent or was future attendance at USU planned? What factors were most important and least important in making the decision to change to a college-related alternative? What factors were most important and least important in making the decision to change to a non-college alternative? Were future plans, following the present course of action, decided or undecided? What effect did location have on college decision plans? To what extent were the college decision changes rational? It was found that the 768 late adolescents who changed their decision to attend USU in the fall of 1969, chose a variety of alternative courses of action. Nearly half of these Ss chose to attend another college or university, while another one fourth chose to enroll at USU at a later date. Thus, nearly three fourths of the Ss remained within the domain of their original decision, that being to attend college. The Ss most often saw themselves as being the primary influencers of their decisions, with friends and fathers being less frequently mentioned influencers. Religious advisors, recruiters, and employers were least frequent primary influencers. It was seen that nearly 4d% of the decision changes not to enroll at USU were permanent, while another approximate 40% were temporary -- the Ss having already enrolled or planning to enroll at USU in the future. Expenses, location, and financial aid were the leading factors determining college choice, and housing, social opportunities, and recruitment were least important factors. The most important factors leading to the selection of non-college alternatives were basic indecision and doubt about college attendance, and financial and practical considerations. As to continued future planning in the development of these late adolescents, it was found that approximately 70% did have definite plans for the future, whereas 30% were undecided or gave no response. Two thirds of the Ss who changed colleges chose to attend another college located within the state of Utah, with the remaining choices covering a wide geographical area. Considerable variation in the degree of rationality in these decisions was implied by the factors that did or did not influence their decisions. The model of Koontz and O'Donnell for rational decision making was applied, but adult models may not be appropriate for the late adolescent stage of development. The results were discussed in relation to the literature reviewed and recommendations were made for future research.