Despite the importance placed on how children come to solve single-digit addition problems, many children count on to solve these problems when they are expected to use accurate retrieval-based strategies. In this study, we assessed if a subitising intervention improved the rate at which problem-solving practice promoted retrieval, using a multiple baseline across participants design. For two of three participants, problem solving practice was initially ineffective for promoting retrieval before the intervention but after the intervention, retrieval increased significantly as a function of practice. We also examined possible reasons for why this occurred.