sentences: There is an increased awareness of the roles that e nterprise architecture (EA) and enterprise systems (ES) play in today ’s organizations. EA and ES usage maturity models are used to assess how well c ompanies are capable of deploying these two concepts while striving to achi eve strategic corporate goals. The existence of various architecture and ES usage models raises questions about how they both refer to each other, e.g. if a higher level of architecture maturity implies a higher ES usage level. This paper compares these two types of models by using literature survey results and case-study experiences. We conclude that (i) EA and ES usage maturity model s agree on a number of critical success factors and (ii) in a company with a mature architecture function, one is likely to observe, at the early stages of ES initiatives, certain practices associated with a higher level of ES usage ma turity.