For decades, Drosophila wing discs have provided a powerful model to interrogate the genetics, signalling and cell biology of epithelial pattern formation and organ size control. In four days of larval development they proliferate from 50 to 50,000 cells and are patterned along their primary axes; the same morphogens that pattern an axis can also regulate cell division. The link between patterning and size control has similarly been investigated in disc tumour models, but how these processes are integrated at the single cell level has been unclear. Now, Yan Yan and colleagues report a single cell analysis of wing discs in normal and tumour conditions. They first generated single cell RNA data for discs at the 10,000-20,000 cell stage. Epithelial cells cluster away from myoblasts and trachea and, within the epithelial cluster, subclusters reflecting different patterning domains are readily distinguishable. In scrib mutants, which form neoplastic tumours, partial proximal-distal patterning does occur even in the context of a totally disordered epithelial tissue architecture. Finally, the authors were able to cluster gene sets involved in regulating proliferation and growth control in both wild type and scrib contexts. This work thus provides a valuable resource – with a web interface for database exploration – for single cell analysis of this premier developmental model.