The adaptive behavior construct has gained prominent attention in human services over the last several years in Portugal, and its measurement has become an integral part of the assessment of populations with intellectual disability. In Portugal, diagnosis remains exclusively based on IQ measures, although some attention recently has been given to the adaptive behavior concept. In this article, we explain the adaptation and validation process of the Portuguese version of the Adaptive Behavior Scale (PABS) on a sample of 1,875 people with and without intellectual disability. Results of the study are discussed in terms of the reliability and validity of PABS on the sample. The PABS appears to be a valid and reliable assessment of adaptive behavior in individuals in Portugal with intellectual disability.