Preliminary Phase I and II trials for the Lidcombe Program of early stuttering intervention have found favorable outcomes and that the treatment is safe. Although speech-language pathologists (SLPs) often need to intervene with pre-schoolers' early stuttering, many of these children will recover at some time in the future without such intervention. Consequently, they need to know whether the Lidcombe Program's effect on stuttering is greater than that of natural recovery. Participants were 23 pre-school children who were randomly assigned to either a control group or a treatment group that received the Lidcombe Program for 12 weeks. A repeated measures ANOVA showed no main effect on stuttering for the group (control/treatment), a significant main effect for the measurement occasion (at the start and at the end of the treatment period), and a significant interaction between group and measurement occasion. Stuttering in the treatment group reduced twice as much as in the control group. These results are interpreted to mean that the introduction of the Lidcombe Program has a positive impact on stuttering rate, which exceeds that attributable to natural recovery.