Factors influencing students' choice of institutions are examined in Part A of the SISFAP studies. The principal empirical base of the study consists of a large-scale longitudinal data file that assesses students' college choices at three time points: the beginning of the 11th grade, mid-way through the 12th grade, and college entry. Multivariate analyses of the data were conducted to determine how the students' institutional choices are affected by (1) student characteristics, (2) the characteristics of the students' higher education environment, (3) state and federal financial aid programs, and (4) student aid packages offered by institutions. Chapters examine: the design of the study; consistency and change in choice behavior; summary of regression analyses; effects of student characteristics; higher education environment; impact of state programs; Basic Educational Opportunity Grants; and effects of financial aid offices. Appendices contain procedures for matching and merging data files, reliability of college admissions test and questionnaires, documentation of the 11th-12th grade-entering freshman longitudinal file, and recent trends in postsecondary access and choice. Among the conclusions were these: although 41.7 percent of students who eventually attend college express no college preferences when they start 11th grade, many of them end up applying to only one college; two students in five apply only to the institution that they enter; student ability appears to be one of the most important factors in college choice; distance from home is a major factor; and Orientals and high-ability students have the most success in implementing early choices. (LC)