Frontal asymmetry (FA), the difference in brain activity between the left versus right frontal areas, is thought to reflect approach versus avoidance motivation. This study (2012-2021) used functional near-infrared spectroscopy to investigate if infant (M[subscript age] = 7.63 months; N = 90; n = 48 male; n = 75 White) FA in the dorsolateral prefrontal cortex relates to psychopathology in later childhood (M[subscript age] = 62.05 months). Greater right FA to happy faces was associated with increased internalizing ([eta][superscript 2] = 0.09) and externalizing ([eta][superscript 2] = 0.06) problems at age 5 years. Greater right FA to both happy and fearful faces was associated with an increased likelihood of a lifetime anxiety diagnosis (R[superscript 2] > 0.13). FA may be an informative and early-emerging marker for psychopathology.