Background: Many South African learners seem unprepared for formal education, and a need for intervention during early childhood has been identified. Aim: The present study explored the effect of infant exposure to an early childhood development programme aimed at the sensory developmental stage of the infant's brain. Setting: Participants were recruited through local baby clinics and nursery schools in the Western Cape. Participants were from the middle-income sector and the sample consisted of 63 infants between the ages of 3 and 12 months--gender representation was approximately equal and 17% of the infants were of mixed race, 8% black and 75% white. Methods: A pretest-posttest design was used involving an intervention group (N = 29) and a control group (N = 34) of infants. There was no known bias in group allocation. Intervention was provided in the form of the Numbers in Nappies programme and cognitive performance was assessed with the BSID (III) before and after the intervention for both groups. Results: The intervention group showed theory expectant increases, most notably on the Cognitive Scale and the Social-Emotional Scale of the BSID (III). The performance of the intervention and the control group on the cognitive subscales (Cognitive, Language and Motor) was compared before and after the intervention. The only significant difference was on the Cognitive Scale after the intervention. Conclusion: The findings indicate that appropriate intervention taps into the cognitive processing potential of infants, thus increasing their cognitive ability and enhancing their social-emotional functioning. The stimulation provided by parents and primary caregivers is essential in enhancing this experience-dependent development and the Numbers in Nappies programme provides a cost-effective intervention suitable for a home environment.