A central theme in the strategic groups literature is that there is a theoretical relationship between groups and firm performance. However, the empirical evidence is conflicting. The aim of this research is to study this linkage through two analysis. Thus, the analysis that has been traditionally used (performance differences between groups) is complemented with an analysis of performance differences within each group. In order to set up strategic groups, we carry out an analysis about the firms operating in the Spanish construction industry, using specific variables associated with Porter's generic strategies.