Despite strong evidence self-regulation skills are critical for school readiness, there remains a dearth of longitudinal studies that describe developmental trajectories of self-regulation, particularly among low-resource and underrepresented populations such as Spanish-English dual-language learners. The present study examined individual differences in trajectories of self-regulation among 459 Spanish-English dual-language learners who were Hispanic from 4 different samples and 3 geographic locations in the United States. Self-regulation was assessed in all samples using repeated administration of the Head-Toes-Knees-Shoulders (HTKS) task from early childhood through early elementary school. Results of latent growth curve analyses revealed that growth was best represented by quadratic trajectories. Latent class growth analyses captured significant individual differences in self-regulation trajectories. One group of children (41%) started with higher HTKS scores and displayed rapid early growth in performance. A similar percentage of children (41%) displayed intermediate growth in self-regulation, starting with lower HTKS scores but displaying rapid growth commencing arrange 4.5 years. Finally, about 18% of the sample did not display growth in HTKS performance until after entry to elementary school, around age 6 years. Girls were half as likely as boys to be in this later developing group. Likewise, children from families at the upper end of the socioeconomic distribution in this low-income sample were significantly less likely to be in the later developing group relative to children from families with lower SES. Study findings indicate the importance of monitoring growth rates in self-regulation as a means of identifying children at risk for entering school without the requisite self-regulation skills.