This volume contains the lecture notes from the courses o?ered at the Inter- tional Summer School on Language Engineering and Rigorous Software De- lopment, held in Piriap ´ olis, Uruguay, from February 25 to March 1, 2008. The aim of the schoolwasthe dissemination of advancedscienti?c knowledge in the areas of programming languages and rigorous methods for software - velopment. The school was oriented to computer science graduate students and researchers,withaninterestinformaltechniquesforthedesignandconstruction of software systems as well as programming languages. The school was organized in the context of the LERnet (Language En- neering and Rigorous Software Development) project. LERnet is a project of the ALFA programme of the European Commission for co-operation between higher education institutions of the European Union and Latin America. The institutions that participate in the LERnet project are the following: - Chalmers Tekniska H¨ ogskola, Sweden - Institut National de la Recherche en Informatique et Automatique (INRIA), France - Universidad de Castilla-La Mancha, Spain - Universidad Catol ´ ica de Santiago del Estero, Argentina - Universidad EAFIT, Colombia - Universidade Federal de Minas Gerais, Brazil - Universidade do Minho, Portugal - Universidad Nacional de San Luis, Argentina - Universidad Polit´ ecnica de Valencia, Spain - Universidad de la Republica ´ , Uruguay - Universiteit Utrecht, The Netherlands The project oversees the mobility of PhD students from Latin America to the European Union and vice versa for a period of up to 18 months, to pursue