The use of criterion based assessments to establish baseline skills for developing ABA program goals has been a long established practice. However, in recent years there has been growing use of two specific assessments in the field: the Assessment of Basic Language and Learning Skills- Revised (ABLLS-R) and the Verbal Behavior Milestones Assessment and Placement Program (VB-MAPP). Despite the widespread use of these assessments there is little published research documenting the reliability and validity of these measures. This presentation will share initial pilot data on the reliability and validity of each measure as well as convergent validity between measures. This session will take an in-depth look at the alignment and overlap in items between the two measures and how they are conceptually similar and different in their construct of verbal behavior. Participants will also be provided with recommendations for assessment use, practical strategies for enhancing consistency amongst assessors, and sample fidelity checklists.