Changes in maladaptive behaviors related to specific stages of dementia were investigated in 251 adults 45 years of age and older with Down syndrome. Findings indicate clear differences in maladaptive behaviors at various stages of dementia. Generally, individuals with no signs or symptoms of dementia displayed fewer and less severe maladaptive behaviors than individuals in the early and mid-stages of dementia. Individuals transitioning into the early stages of dementia from no dementia displayed increased aggression, fearfulness, sadness, sleep problems, social inadequacy, stealing, and general regressive behavior. Thus, new concerns regarding these types of behaviors could be particularly useful in clarifying the dementia status of adults with Down syndrome and developing individualized plans for support.