Data-based, theory driven interventions for ASD have varying amounts of evidence supporting their benefits. For example, ABA models of intervention involve direct measurement of teaching targets, and systematic application and evaluation of strategies informed by proven learning principles. ABA is used for all skill domains and across all environments, and spans a continuum from structured to naturalistic methods of instruction. Choice and evaluation of the effectiveness of programming decisions should be informed by on-going data collection. If the teacher is uncertain about the interpretation of data or the best course of action her supervisor should have sufficient experience to help with decision making. The extent to which accurate and valid data are obtained and both parents and programs are committed to the use of databased decision making is an essential part of a good program match. In fact, a good match will be evident to the extent that the data show progress.