The effects on recognition of changes in environmental context between learning and test are examined. A context effect occurs when memory tests that take place in an environmental context that is different from the learning context produce consistent differences in performance. A formal model of context-dependent recognition within a global activation framework is presented. The model generates the predictions that (1) context effects will be present when items are tested in a new context that was not seen during learning and (2) context effects will be absent or very small when items are tested in a context that was experienced during learning but that differs from the context in which the test item was learned. Both predictions were verified in an experiment that varied the nature of the different-context test within subjects. Implications for research concerned with context-dependent recognition are discussed.