Adoption of an information system could be reflected in two ways: through the adoption intentions of the non-adopters and the extent of adoption for the adopters. This study seeks to identify the motivational factors influencing individuals’ adoption intentions and the extent of a system adoption within the context of Open Source Software (OSS). Building on the theoretical underpinnings of the SelfDetermination Theory, we proposed and empirically assessed two conceptual models to examine OSS adopters’ extent of adoption (based on intrinsic and extrinsic motivation) and OSS non-adopters’ intentions for adoption (based on amotivation). Results from the survey collected from 264 OSS adopters and 212 OSS non-adopters reveal that strategy belief amotivation is the major factor for not using OSS (i.e., non-adopters) while identified regulation is the major extrinsic motivation affecting the extent of adoption (i.e., adopters). Interestingly, intrinsic motivation to accomplish and capa...