Electronic ordering (e-ordering) systems are currently being implemented in both private and public organizations. The advantages of these systems are widely acknowledged: increased compliance with use of fewer suppliers and improved efficiency. However, realizing these benefits is difficult due to end-user resistance to adopting and using such systems. The present paper proposes a framework inspired by adaptive structuration theory (AST) that functions as an analytical framework that helps to understand what structures and factors influence adoption and use of an e-ordering system. To the adapted AST framework is added factors of influence found in previous purchasing research, resulting in a framework that helps to understand adoption and use of an e-ordering system over time. The framework is tested using empirical data from a 4-year longitudinal case study. The paper embeds purchasing theory within the structuration framework of AST.