This study investigated the contributions of the professional qualification of biology teachers, laboratory facilities, and biology textbooks to the teaching of biology in 10 government and 10 harambee schools in Kenya. Biology is currently a compulsory subject in all secondary schools in this country. Data were obtained from questionnaires administered to curriculum developers, head teachers, biology teachers, biology laboratory assistants, and students in form four schools. (These questionnaires are included in appendices.) Findings indicate that the more professionally qualified the teacher in a given school the better the performance of students in such a school and that the availability of laboratory facilities helped students understand certain concepts learned in theory classes. Students also performed better in schools which had many different types of textbooks available to teachers and students. In addition, students performed better in schools in which they did not have to share their textbooks. Several recommendations based on these and other findings are offered. One recommendation is to supply syllabi and teaching guides to all schools, especially those with untrained teachers. (JN)