The purpose of this study was to determine the effects resulting from the presence or absence of living material in the biology classroom on knowledge of biology and attitudes toward science and sciencing. An experimental design employed random assignment to treatment and control groups. A separate-sample pretest-posttest control group design was used with 111 biology students from a medium-sized suburban high school. The treatment was administered for 16 weeks. The treatment group held class in a room containing live plant and animal displays attractively maintained. The control group students held class in a general purpose classroom containing no living materials. Students in the treatment group performed higher on both dependent measures (knowledge of biology and attitude toward science and sciencing) than those in the control group. The findings are interpreted as suggesting that living displays in the classroom serve to stimulate interest and curiosity which in turn influence attitude and achievement.