In this population-based study, we assessed the relation between socioeconomic and psychosocial conditions in 1,094 pregnant women and subsequent infantile colic by means of self-administered questionnaires measuring exposures in the 17th pregnancy week and telephone interviews at infant age 5 weeks. There was a higher risk of colic in infants born to younger mothers, mothers with low instrumental support in pregnancy, and mothers with nonmanual occupations. Having an "active" job situation, that is, high demands and high decision latitude at work, acted synergistically with a nonmanual occupation, yielding even higher odds ratios for colic as did concomitant low instrumental support and nonmanual occupation. An expected synergy between low social participation and nonmanual occupation could not be demonstrated. Findings from gender-related research may partly explain some of these results.