Investigated were (1) how participation in a particular program in biology affected student attitudes toward science and toward the study of science, and (2) whether the student participants in this program developed an understanding of the processes of science. Students in six high schools were involved in this investigation. An investigator-developed questionnaire assessing attitudes toward science was administered twice during the year. Data also included student reports of critical incidents and pre and post-scores from the Processes of Science Test. The results indicated that (1) high interest in science at the outset was maintained throughout the instructional period; (2) interest intensity increased for girls, but not for boys; (3) three of the 136 elements composing the instructional semi-system were accepted by students as especially worthwhile; and (4) that students strengthened their self-image as science students, but that this was not clearly accompanied by a commensurate increase in their actual abilities in science. Concluded were that (1) students found value in long-term projects involving a clearly defined central theme carried throughout a series of investigations and (2) laboratory activities and teacher-student conversations relating biology to student affairs were of value. (RS)