Background: Behavioural problems in individuals with intellectual disabilities have a negative impact on them. Limited assessment measures exist in Spain. This study aimed to validate the Behavior Problems Inventory--Short Form (BPI-S) in the Spanish population by examining its psychometric properties and factorial structures. Method: This study included 458 individuals with intellectual disabilities evaluated by 137 professionals. The validity and reliability of the scale were examined. Results: The validity of the measurement tool confirmed a three-factor model. Significant correlations were observed between problem behaviours and maladaptive behaviour indicators, with negative associations found between problem behaviours and adaptive behaviour scores. Conclusions: The Spanish version of the BPI-S demonstrated good internal consistency and convergent and discriminant validities. The most common behaviours were identified, and the scale was refined to 28 items. The three-factor model showed an acceptable fit. Further research is required to establish clinical norms and explore the factorial structures.