With the burgeoning casualisation of the higher education workforce, the precarious nature of casual teaching has become increasingly well documented. Universities are recognising that enhancing quality learning and teaching must include attention to the provision of services, support, and professional development for teachers employed on a sessional or casual basis. This paper presents a study investigating an online course for supporting and connecting dispersed and diverse casual teachers at an Australian university. The study explores the role of community and the impact of professional development for casual teachers across discipline boundaries in an institution-wide online course.