In this article, the authors focus on issues of instruction in classrooms. Initially, a brief definitional and historic section is presented. This is followed by a discussion of four assumptions about the current state of affairs: (a) evidence-based practices should be identified and used, (b) children's phase of performance should dictate practice selection, (c) naturalistic procedures should be used, and (d) play is a defensible curricular domain. Three challenges (instructional, experimental, and resources) are noted.