OBJECTIVE This study investigated the effectiveness of a parent-implemented intervention on children's speech-language development and parents' interaction styles. METHODS Seventeen children with cleft palate (CP) and their mothers participated in all sessions of a parent-implemented intervention program. Nine children with CP and their mothers who did not receive the intervention were included to examine the full effectiveness of the program. The intervention program consisted of four phases, pre-intervention test, parent training, parent-implemented intervention at children's home for 3 months, and post-intervention test. Children's language and speech measures and maternal measures from pre- and post-intervention tests were compared between groups (intervention vs. no intervention). RESULTS Children who received a parent-implemented intervention exhibited significant improvement in language measures based on standardized tests and quantitative language and speech measures from spontaneous utterances. The children in the intervention group showed a significantly greater extent of change in expressive vocabulary size, number of total words, and mean length of utterance than did those who did not receive the intervention. Mothers who received the training showed a significantly decreased number of different words, increased responsiveness, and decreased non-contingent utterances for children's communication acts compared to those who did not receive the training. CONCLUSIONS The results of the study support the effectiveness of parent-implemented early intervention on positive changes in children's speech-language development and mothers' use of communication strategies.