Retrospective recall about children’s symptoms is used to establish early developmental patterns in clinical practice and is also utilised in child psychopathology research. Some studies have indicated that the accuracy of retrospective recall is influenced by life events. Our hypothesis was that an intervention: speech and language therapy, would adversely affect the accuracy of parent recall of early concerns about their child’s speech and language development. Mothers (n = 5,390) reported on their child’s speech development (child male to female ratio = 50:50) when their children were aged 18 or 30 months, and also reported on these early concerns retrospectively, 10 years later, when their children were 13 years old. Overall reliability of retrospective recall was good, 86 % of respondents accurately recalling their earlier concerns. As hypothesised, however, the speech and language intervention was strongly associated with inaccurate retrospective recall about concerns in the early years (Relative Risk Ratio = 19.03; 95 % CI:14.78–24.48). Attendance at speech therapy was associated with increased recall of concerns that were not reported at the time. The study suggests caution is required when interpreting retrospective reports of abnormal child development as recall may be influenced by intervening events.