The paper concerns the way in which the factors influencing transformation toward or away from modularity, described in general modular systems theory, appear in the context of social and health services, and the extent to which the special characteristics of this context might support or prevent the application of modularity. The arguments constructed are based on the literature on modularity in products and services, which is reflected upon in the light of the special characteristics of health services presented by health economists. Combining these two perspectives reveals interesting insights supporting the application of modularity, such as demand based policies and choice option. However, theoretical analysis reveals also problems. Characteristics of health economic tend to be negatively related to increasing modularity of health services. This paper enhances understanding of how catalysts of modularity emerge in health services, and of what needs to be taken into account in applying modularity in this context.