The effects of five factors on the sensitivity of 36 women to infant cries were studied. The variables were listener experience (none, one month, four months), age of crying infant (one month, four months), type of cry (tired, angry, hungry), cry typicality (prototypical, moderately typical) and cry length (fixed, variable). A five-way analysis of variance was performed after scores were converted to the signal detection measure of sensitivity, d′. In addition to several main effects, significant age of infant × typicality × cry type, typicality × listener experience, and typicality × cry length interactions were found. The finding of an influence of cry length provided a possible explanation for the discrepancy in results in the infant cry literature, since the better discriminated single cries of variable length were typical of those cry signals used in studies reporting successful discrimination, and the poorly discriminated 15 sec fixed-length cry sequences were typical of those used in the studies failing to find discrimination of infant cries.