This study reports on a program to train student clinicians to provide recast therapy on complement clauses to children with developmental language disorder (DLD). To determine the efficacy of the program, we conducted secondary data analysis based on Owen Van Horne et al. (2023) and examined student clinicians' recasts after training and children's progress after treatment. Three student clinicians received a two-stage training, followed by a real intervention program targeting complement clauses in six children with DLD. A third of the intervention sessions were coded for the total number and number of unique verbs in complement clauses provided by the student clinicians. An elicited production task was completed to test children's knowledge of the target structure. On average, student clinicians provided 30 targeted recasts to each child during each intervention session. They provided a greater number of and more variable input for that compared to WH complements. Children demonstrated significant improvement only in WH, but not in that, complements. A targeted training program could strengthen clinicians' ability to provide recast therapy on complex syntax; however, future refinements should shorten and broaden training to include more targets. A mismatch between input patterns and learning patterns was observed. WH complement input is more stable than that input, given the less variable complement-taking verbs provided by the student clinicians and the overtness of the WH word as a stable complementizer, which may have facilitated the identification and extraction of the target syntactic structure.