This document discusses human capital investment and return on investment. It defines human capital as consisting of ability, knowledge, skills, talent, behavior, and effort over time. Return on investment in human capital can come in both transactional and relational forms. Transactional ROI involves explicit rewards exchanged for work, while relational ROI depends more on relationships within an organization and includes intrinsic rewards. The document presents models showing how commitment, engagement, and human capital investment can lead to improved performance and ROI.