Challenging behavior is one of the largest barriers to ensuring that people with intellectual disabilities (ID) are able to participate in the community. These difficulties have become one of the main causes of social exclusion. The research into and treatment of challenging behavior has usually involved the identification of its function and the manipulation of the events or environmental conditions that influence its occurrence (antecedent variables). The present research explores the relationship between antecedents and behavioral function and the extent to which antecedent variables may act as predictors of behavioral function. This relationship is explored using two standardized instruments: Questions About Behavioral Function and Contextual Assessment Inventory. Data from the validation of these instruments for the Spanish population involved 300 participants with ID and 328 challenging behaviors. The results suggest that social/cultural variables are most related to challenging behavior, whereas biological variables seem to only be related to physically maintained behavior.