Lessons learned from the process of the ICZM Strategy as part of the socioecological system of the Mar Menor (Murcia, Spain) may well be of interest to coastal managers. ICZM Strategy was one of the instruments chosen by the regional government of Murcia to deal with the critical situation of the largest lake in the western Mediterranean. Human activities that exert most pressure are those related to agriculture, urban growth and tourism-leisure. The Mar Menor is identified as a socioecological system defined through its river basin. The conceptual frameworks followed for the model of public management of the lagoon and its surroundings were DPSIWR and the Decalogue of ICZM. The scheme of work provides some lessons learned from previously analysed parts: (a) background and institutional arrangements, (b) operational diagnostic model, (c) strategic diagnosis, (d) proposals and (e) the participatory process. Additionally, the process of institutionalisation allows for other lessons to be learned. The document was finalised in 2016, and it has been further developed in order to become institutionalised. During this period of time, the regional government has already implemented actions that coincide with the proposals of the strategy, informing us that some instruments can start working before being officially approved.