Preschoolers' inhibitory control and early math skills were concurrently and longitudinally examined in 255 Chinese, African American, Dominican, and Mexican 4-year-olds in the United States. Inhibitory control at age 4, assessed with a peg-tapping task, was associated with early math skills at age 4 and predicted growth in such skills from age 4 to age 6 among these ethnic minority children after adjusting for ethnic background. Chinese children outperformed other groups on inhibitory control at age 4 and early math skills across ages. Mediation analyses indicated that their advanced inhibitory control at age 4 partially accounted for their advantage in early math skills concurrently at age 4 and longitudinally at age 6, highlighting the role of inhibitory control in the early math skills of ethnic minority children.