For preschool-aged children at-risk for literacy difficulties, we examined whether classroom and home environments were jointly associated with literacy skill gains and whether environments moderated response to intervention (n = 281). We first used a person-centered approach to characterize children's classroom and home environments, identifying three profiles based on variations in the home, but not classroom, environment. We then used a variable-centered approach to evaluate the association of environments with child gains, considering both statistical significance (p < 0.05) and practical meaningfulness (d > 0.20). Classroom instructional supports were a practically meaningful moderator of response to intervention for letter writing. Home code-focused teaching and shared reading activities were statistically significant moderators of response to intervention for print knowledge. Home shared reading activities were a practically meaningful moderator of response to intervention for phonological awareness and letter writing. Although not jointly, classroom and home environments individually contributed to response to intervention. Findings suggest children in classrooms with lower quality instructional supports and children receiving more shared reading activities at home may benefit from small-group early literacy interventions. Literacy gains from interventions may be better realized when these environments are considered. [This paper will be published in "Reading & Writing Quarterly."]