Current literature on ASD-ADHD co-occurrence is strongly biased on childhood. ASD/ADHD constellations peak during adolescence, driven by those who still have the symptoms. Strong emphasis in this developmental periodon social adaptation and executive functioning may explain this pattern. Adolescence may be –after early childhood– a second crucial time window for change in symptoms (for better or worse). A full lifespan approach towards ASD-ADHD co-occurrence into old age brings novel opportunities.