Enterprise Resource Planning systems are business systems that are expected to integrate all the business’ processes within organization, and since ERP systems are complex and re-quire extensive changes in the organization, it is crucial that the implementation is success-ful. However, the implementation of ERP systems is described as both risky and complex projects.

The purpose of this master thesis is to investigate the importance of different critical success factors across the ERP project life cycle within SMEs. Furthermore, we will compare our findings to see if there are differences between larger corporations in the USA and SMEs in the county of Jönköping, Sweden and try to explain the potential differences.

In order to fulfill our purpose, we used a quantitative approach to collect primary data from the SMEs in the county of Jönköping. Our data was thereafter qualitatively analyzed in order to describe our findings.

The conclusions drawn in this thesis is that the following critical success factors are per-ceived to be most important within the SMEs investigated:

• Infusion stage: Careful selection of package

• Adoption stage: Top management support

• Adaptation stage: Project champion

• Acceptance stage: Project champion

• Routinization stage: Education on new business processes

• Infusion stage: Vendor support.

It was apparent that the critical success factors identified in our research differed from the critical success factors identified for the Fortune 500 companies in the USA. However, we have failed to find any valid and reliable reasons for the differences even though we have discussed possible reasons for them.