In order to determine and analyze the impact and influence that a specific National Science Foundation (NSF) summer institute at the University of Montana had, questionnaires were sent to the 109 participants who obtained the M.S.T. degree for teachers of biology and also to a control group of teachers made up of randomly selected non-NSF trained teachers. Data obtained from both groups yielded the following information: (1) participants' students spent more time carrying out laboratory investigations than those in the control group; (2) the majority of the NSF participants changed their teaching philosophy from a traditional to a Biological Science Curriculum Study (BSCS) inquiry type philosophy, as well as making greater use of BSCS materials than did the control group; (3) participants increased their reading of some science journals due to institute involvement; (4) one hundred percent of the responding participants claimed that they gained new insights into teaching from their association with other biology teachers at the institute; and (5) NSF participants were able to attain most of the personal goals mentioned by the institute applicants: strengthening one's science background, obtaining a master's degree, gaining a knowledge of modern developments in science and gaining new techniques and methods for teaching. (Author/EB)