Purpose: Clinicians do not have an evidence base they can use to recommend optimum intervention intensity for preschool children who present with speech sound disorder (SSD). This study examined the effect of dose frequency on phonological performance and the efficacy of the multiple oppositions approach. Method: Fifty-four preschool children with SSD were randomly assigned to one of three intervention conditions. Two intervention conditions received the multiple oppositions approach either 3 times per week for 8 weeks (P3) or once weekly for 24 weeks (P1). A control (C) condition received a storybook intervention. Percentage of consonants correct (PCC) was evaluated at 8 weeks and after 24 sessions. PCC gain was examined after a 6-week maintenance period. Results: The P3 condition had a significantly better phonological outcome than the P1 and C conditions at 8 weeks and than the P1 condition after 24 weeks. There were no significant differences between the P1 and C conditions. There was no significant difference between the P1 and P3 conditions in PCC gain during the maintenance period. Conclusion: Preschool children with SSD who received the multiple oppositions approach made significantly greater gains when they were provided with a more intensive dose frequency and when cumulative intervention intensity was held constant. (Contains 2 figures and 5 tables.)