This volume contains the proceedings of MPC 2004, the Seventh International Conference on the Mathematics of Program Construction. This series of c- ferences aims to promote the development of mathematical principles and te- niquesthataredemonstrablyusefulinthe processofconstructingcomputerp- grams, whether implementedinhardwareorsoftware.Thefocus isontechniques that combine precision with conciseness, enabling programs to be constructed by formal calculation. Within this theme, the scope of the series is very diverse, including programmingmethodology, programspeci?cation and transformation, programming paradigms, programming calculi, and programming language - mantics. The quality of the papers submitted to the conference was in general very high, and the number of submissions was comparable to that for the previous conference. Each paper was refereed by at least four, and often more, committee members. This volume contains 19 papers selected for presentation by the program committee from 37 submissions, as well as the abstract of one invited talk: - tended Static Checking for Java by Greg Nelson, Imaging Systems Department, HP Labs, Palo Alto, California. The conference took place in Stirling, Scotland. The previous six conferences wereheld in1989inTwente, TheNetherlands;in1992inOxford, UK;in 1995in KlosterIrsee, Germany;in 1998in Marstrandnear Got ] eborg, Sweden;in2000in Pontede Lima, Portugal;and in 2002in Dagstuhl, Germany.The proceedingsof these conferences were published as LNCS 375, 669, 947, 1422, 1837, and 2386, respecti