BACKGROUND: Prior studies document strong interactions between emotional and mnemonic processes. These interactions have been shown to vary across development and psychopathology, particularly mood and anxiety disorders. METHODS: The present study used functional neuroimaging to assess the degree to which adolescents and adults differ in patterns of neuronal engagement during implicit encoding of affective stimuli. Subjects underwent rapid event-related fMRI while viewing faces with angry, fearful, happy, and neutral expressions. A surprise post-scan memory test was administered. RESULTS: Consistent with previous findings, both adolescents and adults displayed engagement of left ventrolateral prefrontal cortex when viewing subsequently recognized stimuli. Age differences emerged in patterns of neuronal activation associated with subsequent recognition of specific face-emotion types. Relative to adults, adolescents displayed more activity in the anterior cingulate when viewing subsequently remembered angry faces, and more activity in the right temporal pole when viewing subsequently remembered fear faces. Conversely, adults displayed more activity in the subgenual anterior cingulate when viewing subsequently remembered happy faces and more activity in the right posterior hippocampus when viewing subsequently remembered neutral faces. These age-related differences emerged in the absence of differences in behavioral performance. CONCLUSIONS: These findings document developmental differences in the degree to which engagement of affective circuitry contributes to memory formation.