This study addresses questions such as: -- What technological, market, and legal interactions have created the current state of DRM-protected music? -- What security, autonomy, and other concerns make interoperability more or less desirable in the DRM context? -- How can we assess competing approaches to interoperability? Although our economic analysis is inconclusive, for policy reasons we find DRM interoperability desirable; a blended approach combining private-sector efforts with limited government involvement, such as through consumer protection or competition law, is optimal. Available for download at: http://papers.ssrn.com/sol3/papers.cfm?abstract_id=1033231