On their own, the cognitive psychology and sociocultural constructivist perspectives fail to furnish a complete account of adult learning and development. In the past, these perspectives have been viewed as being incompatible because their origins reside in rival and distinct areas of theorising. This paper seeks to propose a more comprehensive basis for adult learning and development by advancing an initial reconciliation between these perspectives which represent views about the internal processes of the mind and the external influence on cognition. This reconciliation is achieved by identifying areas of commonality and compatibility between these two constructivist perspectives which provides a likely basis to yield a more comprehensive account of adults thinking and acting. It is held that only through an accommodation between social practice and cognition can such an account be realised. Differences between the two perspectives are drawn closer together by current theorising which views individual's appropriation of knowledge as being a socially-mediated, interpretative and contested process. This, along with the concept of ontogeny or life history permits closure between the Piagetian and Vygotskian perspectives as they render key differences compatible. It is advanced therefore that deliberations about adults' construction of knowledge and ongoing development needs to account for the dual contributions of internal processes and external sources provided by both constructivist perspectives.