Service-learning as a transformative pedagogy has been adopted within Hong Kong's tertiary education sector for over a decade; however, the lack of a standardized and validated measurement instrument to assess its student learning outcomes has been an obstacle to its further development. The current research study, collaboratively conducted by Lingnan University, The Hong Kong Polytechnic University, Hong Kong Baptist University, and The Education University of Hong Kong, therefore aims to develop such a measurement instrument named the "Service-Learning Outcomes Measurement Scale (S-LOMS)," taking consideration of the unique features of service-learning in Hong Kong. The scale development and validation work, with exploratory factor analysis and reliability test, has thus far demonstrated that the student-perceived learning outcomes after service-learning can be measured and assessed through 56 items. These items cover 11 domains under four major categories, namely: a) knowledge application; b) personal and professional skills, including relationship and team skills, creative problem solving skills, self-reflection skills, and critical thinking skills, c) civic orientation and engagement, including sense of social responsibility, community commitment and understanding, and caring and respect, and d) self-awareness, including self-efficacy, self-understanding, and commitment to self-improvement. Several additional insights arising from the validation results are discussed.