In information systems development, end-users have shifted in their role: from consumers of information to informants for requirements to developers of systems. This shift in the role of users has also changed how information systems are developed. Instead of systems developers creating specifications for software or end-users creating small software programs to operate independently, development is moving towards end-user development that integrates into a platform-based information system. This study defines this type of development as co-creation. Building on the knowledge-based view with co-creation as a knowledge integration mechanism, this research explores co-creation, its drivers, and its impact on system implementation success. System implementation success is extended to explain three dimensions of success: implementation efficiency, implementation effectiveness, and implementation agility. Implementation efficiency requires meeting the performance expectations while remaining within the project time and budget constraints. Implementation effectiveness measures the extent to which the implemented information system meets the information needs of the end-users. Implementation agility is the ability of the information system to be modified to meet the changing needs of the organization. By defining success in a more granular manner, this research enables a richer understanding of implementation success of all information systems, not only those co-created. This study examines the co-creation of electronic health records systems, a platform for capturing, storing, and using medical records within healthcare organizations. It theoretically develops a model of co-creation. Using a survey to collect data and PLS-SEM to analyze the data, the hypotheses are tested. Co-creation mediates the effect of peripheral knowledge, which is the end-user's knowledge of systems development, on implementation effectiveness. Co-creation also partially mediates the effect of platform modularity on implementation effectiveness. Co-creation also mediates the effect of organizational context complexity on implementation effectiveness. These findings demonstrate the importance of understanding co-creation, emphasize training to build peripheral knowledge, and show the importance of modularity in design of platforms. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]