The purpose of this study was to develop and test a factor analysis procedure for sequencing self-instructional materials associated with concept attainment. The effects of a computer-generated psychological sequence compared with a random sequence of concepts on sequential decision-making by three achievement levels of students were determined. The first phase of the experiment included 126 students in seven randomly selected Pennsylvania high schools. In each school three randomly sequenced self-instructional booklets were given to equal numbers of junior and senior vocational agriculture students. Student responses to 30 questions on 10 human relations cases and 30 questions on generalized concepts of an agricultural business situation were analyzed to generate the psychological sequence of concepts which was tested against a random sequence with 294 junior and senior students in 15 schools in the second phase. Reading comprehension test scores and human relations aptitude test scores were used as controls in an analysis of covariance design. When compared with the random sequence, the psychological sequence did not result in significantly higher scores at the .05 level of significance when all data were considered. The effect of sequence in instructional materials was specific to the achievement level of the students and the difficulty level of the materials. This Ph.D. thesis was submitted to The Pennsylvania State University. (WB)