This entry explores how scientific models represent what is possible; how they are justified; and their functions. Two different approaches to these issues are discussed: the first concerns models “embedded” in a well-confirmed theory; the second concerns models not so embedded. When the former models represent possibilities, they provide us with information about what is possible according to the theory in which they are embedded. They are justified to the extent that the theory is actually confirmed. Models of the second kind cannot rely on theoretical support in the same way. Yet, scientists regularly extract modal information from such models, and they hold some epistemic merit. What could underwrite their justification is explored. Finally, various functions played by scientific models that represent possibilities are considered.