Using an experimental study design (N = 41), we examined whether participation in an informal writing assignment, specifically writing a letter to a friend about course content, improved exam scores in an undergraduate child development course. Findings indicated that participating in the writing assignment significantly improved scores on an exam which included both a multiple-choice component and an essay. No effect emerged for a quiz that included only multiple-choice questions. These findings indicate that writing assignments that require students to summarise and paraphrase newly-learned material may improve performance on exams that have a written component to them. (Contains 3 tables.)