Background: Adolescent self-harm is a major public health issue internationally. Various factors associated with adolescent self-harm have been identified, including being bullied and experiencing mental health problems. Stuttering and speech sound disorder are associated with both of these factors. It was hypothesized that both stuttering and speech sound disorder would be associated with self-harm. This is the first study to explore the relationship between communication disorders and adolescent self-harm. Method: Secondary analysis of a large, longitudinal, prospective, community sample, the Avon Longitudinal Study of Parents and Children, was carried out. Clinicians identified children who stuttered or exhibited speech sound disorder at the age of 8 years. When the cohort members were 16 years old, they were asked to complete a questionnaire about self-harm. Multinomial logistic regression was used to examine the associations between stuttering and speech sound disorder and the self-harm outcomes, adjusting for other relevant factors. Results: Of 3,824 participants with data for both speech status and self-harm, 94 (2.5%; 95% confidence interval [CI; 2.0, 3.0]) stuttered at 8 years of age and 127 (3.3%; 95% CI [2.8, 3.9]) displayed speech sound disorder. Speech sound disorder at the age of 8 years was associated with self-harm with suicidal intent in both unadjusted and adjusted models. Differences between the adjusted and unadjusted models were small, suggesting that speech sound disorder is largely an independent risk factor for self-harm with suicidal intent. Stuttering at the age of 8 years was not associated with adolescent self-harm, and there was no association between speech sound disorder and self-harm without suicidal intent. Conclusion: Compared with individuals without speech sound disorder, adolescents with speech sound disorder at the age of 8 years have twice the risk of reporting self-harm with suicidal intent, even when other important predictors are taken into account.