Playgroups are widely used throughout the Australian community yet understanding of their efficacy is hindered by inconsistent playgroup definitions and practice principles. This study aimed to develop, implement and evaluate the feasibility of a manualised therapeutic playgroup for children with developmental delay and their families using a three step process. Step one, manual development, involved triangulating findings from playgroup literature and utilising a working group of professionals (n = 10) and caregivers (n = 2) to identify practice principles and inform the content of a manualised playgroup. Step two, conducted a feasibility study involving parents (n = 9) and children (n = 8); with findings informing step three, manual revisions, in preparation for larger-scale efficacy testing. Step one resulted in the development of an 8-week manualised playgroup for children with developmental delay. In step two, playgroup participants demonstrated improvements in family support and child performance, with playgroup reported as being beneficial by both parents and facilitators. This perceived benefit was attributed to parents’ shared experience, access to skilled facilitators, parent learning and child enjoyment. In step three these findings were incorporated, finalising the manual. In a context where playgroup research is limited by model variability and poorly defined practice principles, this is the first study to systematically develop, implement and pilot a manualised therapeutic playgroup intervention for children with developmental delay. It provides an evidence-based definition of playgroup principles, delivers sufficient assurance of playgroup feasibility to warrant a larger definitive trial, and outlines a process for developing and testing the feasibility of a manualised, complex intervention.