Purpose Differences in communication development impact long-term outcomes of children with autism. Previous research has identified factors associated with communication in children with autism, but much of the variance in communication skill remains unexplained. It has been proposed that early differences in sensory responsiveness (i.e., hyporesponsiveness, hyperresponsiveness, and sensory seeking) may produce "cascading effects" on communication. Evidence for this theory is limited, however, as relations between sensory responsiveness and communication in the earliest stages of development have not been well established. The purpose of this study was to evaluate (a) whether infants with a heightened likelihood of autism diagnosis (i.e., infants with an older sibling with autism) differ from infants at general population-level likelihood of autism (i.e., infants with an older, nonautistic sibling) on patterns of sensory responsiveness, (b) whether early sensory responsiveness is correlated with concurrent communication, and (c) whether the aforementioned between-groups differences and associations are moderated by age. Method Participants were 40 infants (20 infants with an older sibling with autism, 20 infants with an older, nonautistic sibling) aged 12-18 months. A series of observational and parent report measures of sensory responsiveness and communication skill were administered. Results Group differences in sensory responsiveness across the 12- to 18-month period were limited (i.e., only observed for one measure of hyporesponsiveness), though selected differences in sensory responsiveness (i.e., parent-reported hyperresponsiveness and sensory seeking) emerged between groups over this developmental window. Parent-reported hyporesponsiveness was unconditionally, negatively associated with communication skills. Associations between expressive communication and (a) parent-reported sensory seeking and (b) an observational measure of hyperresponsiveness were moderated by age. Conclusions This study provides new insights into the nature of sensory responsiveness and theorized links with communication skill in infants at elevated and general population-level likelihood of autism diagnosis. Further work is needed to better characterize the effects of interest in a larger sample spanning a wider age range. Supplemental Material https://doi.org/10.23641/asha.14515542.