Enterprise Content Management (ECM) is requisite technology for issues of compliance, governance, and business process efficiency. However, the implementation of ECM systems (ECMS) confronts organizations with a manifold of challenges. Particularly the multiplicity and diversity of digital content captured within an organization makes a tailored ECMS adoption difficult. In this paper we state that conceptual models may serve as a means for the structured analysis and design of ECMS. On the basis of a literature review, we derive specific requirements for content modeling and show that these requirements are not met by conventional modeling languages. We therefore introduce ECML, the Enterprise Content Modeling Language, which is specified by means of meta-modeling and illustrated on the basis of an exemplary application.