The mother-infant communicative speech of a group of mothers of 4-month-old first-born twin infants was compared to the speech of a group of mothers of first-born singleton infants. Maternal groups were matched on age, education level, mother-infant attachment status and infant gender, and maternal depression was assessed as a control variable. Maternal speech was coded for focus, content, complexity and syntax of mothers' utterances. The findings of earlier studies with toddler age twins, that maternal speech style was more directive and less infant-focused, were replicated in this prelinguistic period of infancy. Compared to mothers of singletons, mothers of twins used less infant-focused speech, were less responsive to their infants' cues, and attributed less agency to their infants. Mothers of twins also used fewer questions and requests but did not differ from mothers of singletons in their use of negatives and imperatives. These early differences in the language learning environments of twin and singleton infants may be due to the reduced opportunities that mothers of twins have to establish dyadic communicative routines with their infants and to familiarize themselves with their infants as interactive partners, and may have implications for the early language development of twins.