This volume constitutes the proceedings of the 4th IFIP WG 8.1 Working Conference on the Practice of Enterprise Modeling, held in Oslo, Norway, during November 2-3, 2011. The conference series is a dedicated forum where the use of enterprise modeling (EM) in practice is addressed by bringing together researchers, users, and practitioners in order to develop a better understanding of the practice of EM, to contribute to improved industrial EM applications, and to share knowledge and experiences.The 18 papers presented were carefully reviewed and selected from 38 submissions. Authored by both researchers and practitioners, they reflect the fact that EM encompasses human, organizational issues as well as technical aspects related to the development of information systems. The papers are organized in five thematic sessions on process modeling, business modeling, enterprise architecture, EM, and model-driven development. In addition, two keynotes on EM in an agile world and on intra- and inter-organizational process mining complete the volume.