This article investigates the syntactic properties of deponents in finite and nonfinite contexts in several Indo-European languages (Vedic Sanskrit, Ancient Greek, Latin, Hittite, Modern Greek) and proposes a novel definition of deponency: deponents are morphologically nonactive verbs with noncanonical agent arguments that are merged below VoiceP. Since VoiceP is spelled out with nonactive morphology in those languages if it does not introduce an external argument itself, the result is a surface mismatch between morphological form and syntactic function. This proposal predicts that only certain nonfinite forms of deponents will surface with the syntax/morphology mismatch, namely, those that include VoiceP. Nominalizations without VoiceP will appear to suspend the voice mismatch. These predictions are shown to be correct with respect to the behavior of deponent participles in the languages under study.