The purpose of this study was to explore the extent to which rationalistic and institutional considerations affect the decision to adopt information technologies and to explore how adoption rationales relate to the extent of implementation achieved after adoption. A multiple-case study approach was used. Institutional isomorphism rationales were more prevalent than strategic choice rationales. The most extensive implementations were found in organizations with a strategically-oriented rationale for adopting and/or extending use of EDI. The study also found evidence of a shift toward strategic choice rationales for EDI extension. These shifts in rationale originated to some extent in the same institutionally-based mechanisms that motivated the initial decisions to adopt the EDI technology.