This study employs a sequential multiple assignment randomized trial (SMART) design to develop an adaptive intervention with personalized print and digital content for kindergarten to Grade 2 children (n = 273). In Stage 1, we ask whether it is better for children to receive an adaptive intervention based on (a) 10 conceptually coherent texts or (b) 10 leveled texts on a range of topics. In Stage 2, we ask how best to encourage nonresponding children. Findings indicate that children who received either conceptually coherent texts or leveled texts performed similarly on reading comprehension posttests, while augmenting and intensifying follow-up with gamification of the app and text messages to parents improved comprehension outcomes for nonresponders. Descriptively, we find that only 26% (n = 71) of parents accessed the app, highlighting the need for better implementation procedures to increase take up of app-based digital activities.