Objective: Children from low-income families are often not well-prepared for kindergarten entry, especially in mathematical skills. Caregivers may lack the knowledge and confidence to teach early mathematical skills. The purpose of this study was to develop a parent-child activities-based mathematics learning programme and test its acceptability and initial efficacy. Method: The evidence-based Reach Out and Read (ROR) programme was adapted to incorporate mathematics content. ROR plus Mathematics (ROR+M) was developed and introduced during well-child visits. Descriptive and repeated-measures analysis of variance analyses were used to evaluate pre- and three weekly post-intervention assessments. Results: Parents self-reported acceptability and initial efficacy of the ROR+M programme was demonstrated. No change was reported in non-mathematical reading behaviour. Discussion: ROR+M was developed and implemented in a primary care paediatric setting serving primarily low-income families. Acceptability and initial efficacy was demonstrated. Randomised clinical trials are needed before widespread implementation.