This study examined variation in mother–infant interactions, father engagement, and infant cognition as a function of country of origin, socioeconomic status, and English language proficiency in a national sample of Latino infants (age 9 months) born in the United States and living with both biological parents (N=1,099). Differences between Mexican-American infants, who had lower mother–infant interaction scores and less father physical play than did the other Latino infants, were associated with differences in acculturation (both parents' English proficiency). Indicators of acculturation and paternal reports of happiness with partner were associated with paternal engagement. Indicators of acculturation were also related to mother–infant interactions. Infant cognitive scores were associated with maternal interaction but not father engagement, and maternal but not paternal mental health.