E-service development has grown to become a daily practice in most public organizations as a means for realizing digital agendas and e-government initiatives on different levels (local, regional, national and transnational governmental levels). Public e-service development is often an inter-organizational (IO) effort with multiple actors and organizations involved in the multi-faceted dimensions of design, development and delivery decisions. Still, there is a lack of research focusing on IO public e-service development practices in particular. In order to address this lack we elaborate on reported challenges and their implications for IO public e-service development in practice. By returning to two empirical cases of IO public e-service development, the IO dimension is evolved. Our purpose is to highlight challenges in IO public e-service development with implications for research and practice. Findings are presented as eight emerging lessons learned from an inside-out perspective related to phases in IO public e-service development processes.