Drawing on the concept of the "literate environment," the authors conceptualise the numerate environment to explore the development of adults' numeracy. Numerate environments provide opportunities, supports, and demands for numeracy practices. Case studies of domestic energy bills in the UK and of the currency conversion process to the euro in the Slovak Republic from 2009 illustrate opportunities, supports, and demands on adults. We use the idea of affordances to understand inter-relations among these three key aspects. We show the importance of considering affordances at different levels of the environment, which we call here individual, mid-level, and societal or national levels. Implications for numeracy policy and learning are explored.