Software process improvement and software process assessment have received special attention since the 1980s. Some models have been created, but these models rest on a normative approach, where the decision-maker's participation in a software organization is limited to understanding which process is more relevant to each organization. The proposal of this work is to present the MCDA-C as a constructivist methodology for software process improvement and assessment. The methodology makes it possible to visualize the criteria that must be taken into account according to the decision-makers' values in the process improvement actions, making it possible to rank actions in the light of specific organizational needs. This process helped the manager of the company studied to focus on and prioritize process improvement actions. This paper offers an empirical understanding of the application of performance evaluation to software process improvement and identifies complementary tools to the normative models presented today.