This study compares and contrasts the effects of planning on the instructional behaviors of a group of preservice teachers across two teaching conditions, a plan condition and a no-plan condition. Twelve preservice teachers each taught two 25-minute lessons to classes of 7 or 8 fourth-, fifth-, or sixth-grade learners. Lesson plans were developed for the first lesson (plan condition), but not the second (no-plan condition). All lessons were videotaped and subsequently employed in the data analyses. Three data collection instruments were used for the analysis of selected teaching behaviors. Results suggest that planning has a positive effect on some preservice teachers' teaching behaviors. Learners taught in planned lessons spent less time in noninstructional aspects of activity, less time waiting their turn, and less time being off-task during activity time. Teachers were more attentive to the actions of learners during pre-task presentations, and provided specific corrective feedback that was congruent to the skill focus of the lesson more frequently during post-task presentations. For teachers-in-training it seems that planning is important to the employment of effective teaching behaviors in the interactive teaching environment. (Author/LL)