The purpose of this experimental study was to investigate the effects of varied teacher wait-time durations and cognitive questioning levels on student achievement. Thirty preservice teachers taught a science lesson in which the length of wait-time and percentage of high and low cognitive questions were prescribed. The lessions were audio-taped to insure fidelity to the scripted lessons. At the end of the lesson a criterion referenced test was administered. The results of this test were used as the dependent variable. Analysis of achievement results indicated significant differences attributable to teacher wait-time and cognitive questioning level.