In healthy infants, crying behavior is reduced significantly by "supplemental" carrying; that is, increased carrying throughout the day in addition to that which occurs during feeding and in response to crying. To determine whether the recommendation to increase carrying would be effective as a therapy for colic, 66 mothers of infants 4 weeks of age or less who came to their pediatricians with complaints of crying problems ("colic") were randomized to receive standard pediatric advice (standard group) or standard advice plus the recommendation to increase supplemental carrying by 50% (supplemental group). Overall, the supplemental group carried their infants 6.1 hours/d throughout the intervention period, an increase of 2.2 hours/d (56%) more than that provided by the standard group. Despite this significant increase in carrying, there was no difference between groups in the duration or freguency of crying, fussing, or cry/fuss at any time throughout the intervention period. When the greatest treatment effect was expected at 6 weeks, the supplemental group infants cried only 3 minutes less per day (95% confidence interval: 37 minutes less to 32 minutes more per day). We conclude that, compared with standard pediatric advice to be "responsive," supplemental carrying does not reduce crying and fussing behavior further in infants who have colic. In marked contrast to healthy infants, this apparent resistance to increased carrying may indicate an important difference in state regulation and control in infants with colic.