Development of professional skills is essential for success in the new global economy. Equally important is the assessment of the degree to which these skills exist in the future STEM workforce. This Science, Technology, Engineering, and Mathematics (STEM) research and assessment project is a joint effort among Pennsylvania State University, University of Maryland, Florida Atlantic University, and Auburn University. A multi-disciplinary team is developing and testing a set of standardized instruments designed to assess four professional skill areas: Ethics, Teamwork, Global Awareness, and Creative Problem Solving. The basis for this project is the Model of Domain Learning (MDL) that posits three factors (interest, knowledge, and strategic processing) that cross three developmental stages of learning (acclimation, competency, and proficiency). Incorporated into the design and implementation phases of the project is a series of four experimental studies designed to test: (1) the validity and robustness of the MDL framework for assessing professional skills across STEM disciplines, course levels, and instructors; (2) the sensitivity of the instruments to document changes in the development of professional skills; (3) the viability of tracking the development of professional skills using the MDL framework; and (4) the adaptability of the framework with respect to students' progress through their degree programs. The project combines both cognitive and affective dimensions of learning with skill development and is initially focused on engineering, business, information science and technology, and entrepreneurship.