We used a new card procedure to evaluate binocular contrast sensitivity (CS) in 24- and 36-month-old children. The test consists of 40 large (50 by 28 cm) matteboard cards, each of which contains a sine wave grafting with 1 of 5 spatial frequencies (0.4, 0.8, 1.6, 3.2, and 4.8 cpd at 80 cm) and with 1 of 8 contrast levels [from 33% (CS = 3) to 0.4% (CS = 260)]. Estimates of subjects' CS to each spatial frequency were obtained with a modified forced-choice preferential looking (FPL) technique similar to that developed for the Teller Acuity Cards (TAC). All 36-month-olds and 74% of the 24-month-olds completed the entire procedure in an average of 12 min per child. For both groups, the shape of the mean constant sensitivity functions (CSF's) resembled the characteristic inverted U shown by normal adults, except that the toddlers' functions were shifted to lower contrasts and spatial frequencies. Combined with previous results, it appears that the CS cards hold promise as a time-efficient means of assessing CS in infants and young children, and may provide the prototype for a clinical tool to help detect early visual and neurological dysfunction.