This chapter provides an in-depth characterization of the organization and featural make-up of the voice domain. Using restructuring as a probe into the composition of the voice domain, several properties are revealed which provide new or additional support for a number of voice-related assumptions, such as a split voice domain consisting of VoiceP and vP. It is suggested that the heads of the voice domain come with two sets of features, v/Voice-features and ϕ-features, where the former encode differences such as active and passive, as well as specific flavors of the argument or event introducing heads, and the latter identify a DP (the DP valuing the ϕ-features) as an argument of the particular voice head. The chapter proposes detailed structures for passive and restructuring, including morphological spell-out rules for the heads of the voice domain in several languages (Acehnese, Chamorro, Isbukun Bunun, German, Japanese, Mayrinax Atayal, Norwegian, and Takibakha Bunun).