In working with individuals with intellectual and developmental disabilities (IDDs), it is direct care staff who are often required to collect data on individuals' behavior which is used as the basis for implementation of empirically based approaches for intervention and treatment. Due to limited resources, indirect and descriptive measures of challenging behaviors are employed to analyze the function of individuals' behaviors in place of the preferred method of multimodal assessment, which includes experimental functional analysis. To ensure the most effective services and support to individuals with IDDs, accurate and consistent data collection is critical. In this article, we highlight the importance of accurate data collection practices, conduct a comparison of data collection methods, and discuss limitations .… and barriers for staff. The article concludes with recommendations for best practices and future research.