ABSTRACT: Successful formation of long-term declarative memory is influenced, among other things, by attention, emotion, and deviation from expectations. A unique form of expectation can be elicited through musical tension, evoked by the prolongation of certain musical progressions. We examined the effect that musical tension exerts on the formation of declarative memory, by composing three original music pieces that contained tension segments, achieved by delays in release from dominant to tonic harmonies. Music-evoked tension was validated using music information retrieval (MIR) analysis, as well as skin conductance response (SCR) measures. Indeed, tension-evoking musical excerpts were associated with heightened SCR, corroborated by increased subjective ratings of tension, as compared to neutral excerpts. In the main experiment, 50 participants listened to the three musical pieces while they were presented with unique images that were randomly assigned to four conditions: tension, tension-release, neutral music, and silence. One day later, their memory for the images was examined using a recognition test. We found that memory performance was enhanced for images presented during both neutral and tense music compared to silence. Moreover, we observed a tradeoff effect between post-experiment tension perception and memory, such that individuals who perceived musical tension as such displayed reduced memory performance for images encoded during musical tension, whereas tense music benefited memory for those with lower musical tension perception. Understanding the interrelations between musical components, which exert powerful and fundamental responses in humans, and cognitive faculties, may provide insights as to the basic features of memory formation.