PURPOSE: The purpose of this study was threefold: (a) to determine the efficacy of a morphosyntax and a phonology intervention against a no-treatment control group, (b) to assess the effects of those interventions on the nontargeted domain, and (c) to evaluate sequence effects when children receive both interventions. METHOD: Twenty preschoolers with impairments in both morphosyntax and phonology were assigned randomly to an intervention of two 12-week blocks beginning with either a block of phonology first ( n =10) or a block of morphosyntax first ( n = 10). Data were collected at pretreatment, after the first intervention block, and posttreatment. For a control group of 7 children, data were collected at the beginning and end of a time period equivalent to one intervention block. Changes in a finite morpheme composite and target/generalization phoneme composite were assessed. RESULTS: In comparison to the control group, both interventions were effective at a statistically significant level in facilitating improvement in the target domain after 12 weeks. The morphosyntax intervention led to cross-domain change in phonology that was similar to that achieved by the phonology intervention. The morphosyntax first sequence also led to slightly better overall morphosyntactic performance. CLINICAL IMPLICATIONS: Clinically, results suggest targeting morphosyntax first, followed by phonology, if using a block intervention sequence for children with concomitant morphosyntactic and phonological impairments.