This study assesses factors that influence use of suburban school grounds for class-time secondary science instructional activities. Special emphases of the study are on determining frequency of use, factors influencing use, and critical factors limiting use. Results from a survey of secondary science teachers at a public school system in-service meeting indicate that teachers favor the use of school ground science activities, but in actuality, little use of school grounds takes place. The hypothesis is offered that the disparity between teacher preference and teaching practice is a consequence of student discipline problems and large class size. (Author/SA)