In this paper we present results of the impact diagnostic testing and associated context-specific workshops have on students' written communication skills in a graduate-level accounting course. We find that students who undertook diagnostic testing performed better in their first semester accounting subject. This improvement is positively associated with student attendance at context-specific writing skills-based workshops. When we extend the analysis to examine the long-term benefits of participation in the academic development program, there is evidence that diagnostic testing has led to sustained improvement in students' writing ability within their final semester accounting subject. (Contains 11 notes, 6 tables, and 1 figure.)