This study investigated ability-related differences in strategy use and development in the domain of simple arithmetic, in terms of the model of strategic change, using the choice/no-choice method and the chronological-age/ability-level-match design. Twenty-six second-graders with strong mathematical abilities (MA), 25 second-graders with weak MA, and 20 third-graders matched on MA with the strong second-graders solved 36 additions and subtractions with the bridge over 10 in 4 conditions. In the choice condition, children could choose between retrieval, decomposition to 10, and counting on. In the three no-choice conditions, they had to solve all problems with retrieval, decomposition to 10, or counting on. Results revealed differences in strategy use between strong and weak second-graders, but not between strong second-graders and matched third-graders, which indicates that the strategy development of children with weaker MA is marked by a delay. The theoretical, methodological, and practical implications of the study are discussed in detail.