The ability to talk about the internal states (ISs) and feelings of self and other is an age-appropriate development of late toddlerhood hypothesized to reflect toddlers' emergent self–other understanding and to be fundamental to the regulation of social interaction. This study examined the effects of child maltreatment on the emergence of low-socioeconomic status 30-month-old toddlers' IS lexicons. Children's lexicons were derived both from maternal interviews and from observations of children's spontaneous IS utterances in four laboratory contexts. Results from both data sources indicated that maltreated toddlers produced significantly fewer IS words, fewer IS word types, and proportionately fewer IS words denoting physiological states and negative affect than nonmaltreated toddlers. In addition, maltreated toddlers were more context bound in IS language use and more restricted in their attributions of internal states to self and other. Gender differences were also observed. Individual differences in children's IS language production were significantly related to general linguistic maturity in both groups but to toddlers' conversational skills only in the comparison group. In addition, a cumulative risk model describing the effects of the child's attachment relationship with the caregiver on early IS language was tested. Toddlers most severely at risk (maltreated/insecure) had the most compromised IS language. Thus, secure attachment may serve as a protective mechanism against self-dysfunction in maltreated toddlers. © 1994, Cambridge University Press. All rights reserved.