A core feature of Positive Behavioral Interventions and Supports (PBIS) is the collection, summary, and use of data for iterative decision-making. The initial design of support and the adaptations that make behavior support match cultural, organizational, and personal needs require that a support team have functional information to guide decisions. This process has been described frequently for Tier 1 (universal) and Tier 2 (targeted) support systems. In this Evaluation Brief we focus on the extent to which Tier 3 (individual) support teams collect, summarize, and use data to guide implementation of behavior support plans. Our specific focus is a descriptive summary of how elementary school teams use the Individual School Wide Information System (I-SWIS) online application (May et al., 2017) to guide their Tier 3 decision-making as well as general use of PBIS-focused data systems that support overall fidelity to critical components of the PBIS framework. By analyzing data from schools currently engaged in efforts to implement PBIS at Tier 3, we hope to spur further attention to best practices for coordinating evaluation data effectively and efficiently across all tiers and interventions.