One of the education programs for principals in Indonesia is online continuing professional development or CPD. This research aims to understand the participant's perceptions of the effectiveness of online CPD for principals. This study applies the CIPP evaluation. The respondents were 69 principals of primary and secondary schools in Central Java. Quantitative and qualitative data were used in this research. The data were collected using the Likert Scale questionnaire and in-depth interview techniques. The results show that in general, the implementation of online CPD is suitable for the goal of educating the principals and fulfilling their needs. The problems that affect the effectiveness of online CPD are the recruitment system that is not based on participants' competencies in operating e-learning technology, unavailability of internet access in schools, and module determination systems. To ensure the effectiveness of the education process, recruitment of participants should be based on the principals' competencies and school self-evaluations of rather than school supervisor competencies. Furthermore, to ensure that the program is relevant to participants' needs, the sequence of learning material must be determined individually, rather than based on class and region.