The attainment of self-regulatory skills during the toddler years is an understudied issue, especially among low-income children. The present study used growth modeling to examine the change over time and the final status in children's abilities to self-regulate, in a sample of 2,441 low-income children aged 14 to 36 months. Positive growth in their self-regulation occurred between 14 and 36 months, but individual variation was observed in both the growth rates and final status. Children who showed high degrees of negativity at 14, 24 and 36 months grew at slower rates than other children. Boys and children high in negativity had lower scores in self-regulation at 36 months than girls and children with low negativity, whereas higher quality mother-child interactions at 14 and 24 months were associated with better self-regulation at 36 months. The results suggest that some children may be at risk for developing problems in regulation because of mother-child interaction patterns and child characteristics such as high negativity.