This study examined factors related to family, social, and romantic loneliness in 173 undergraduate students (66 males, 107 females). Participants completed measures of attachment style, perceived availability of social support, use of social support coping, and loneliness. Results indicated that participants with greater attachment security reported lower levels of all types of loneliness compared to those with less attachment security, and this was partially mediated by perceived social support but not the use of social support coping. When examining underlying attachment constructs, a more positive model of others was related to less family and social loneliness, and these associations were mediated by greater perceived social support. Model of others also was associated with less romantic loneliness and model of self was associated with less loneliness in all domains, and these relations were partially mediated by perceived social support. Findings are discussed with respect to possible interventions to increase students' perceptions of available social support and to decrease overall loneliness levels.