This book constitutes the refereed proceedings of the 4th International Conference on Model and Data Engineering, MEDI 2014, held in Larnaca, Cyprus, in September 2014. The 16 long papers and 12 short papers presented together with 2 invited talks were carefully reviewed and selected from 64 submissions. The papers specifically focus on model engineering and data engineering with special emphasis on most recent and relevant topics in the areas of modeling and models engineering; data engineering; modeling for data management; and applications and tooling.