The Infant Characteristics Questionnaire (ICQ) was developed as a short, factor-analytic screening device for difficultness. Responses of 322 mothers of 4-6-month-old infants suggested that they regard the fussy, hard-to-soothe, labile infant as difficult. Mother report on the ICQ, particularly on the main fussy-difficult factor was found to have adequate reliability over time and convergence with the Carey Survey of Temperamental Characteristics, with father report on the ICQ, and, to a lower degree, with home data collected by independent observers. It was also found that mother characteristics may affect perceptions of infant difficultness: multiparous, extraverted mothers tended to rate their infants as easy.