This study evaluated a multidimensional model of loneliness as related to risk and protective factors among adolescents with learning disabilities (LD). The authors aimed to identify factors that mediated loneliness among 716 adolescents in Grades 10 through 12 who were studying in high schools or in Youth Education Centers for at-risk populations. There were 334 students with LD, divided into subgroups according to disability severity (three levels of testing accommodations), and 382 students without LD. Five instruments measured participants' socioemotional characteristics: loneliness, Internet communication, mood, and social and academic achievement-oriented motivation. Using structural equation modeling, the results confirmed the loneliness model and revealed that the use of the Internet to support interpersonal communication with friends predicted less intense loneliness, whereas virtual friendships with individuals whom students knew only online predicted greater loneliness. Positive and negative mood and motivation also predicted students' loneliness. In addition, the severity of LD predicted stronger loneliness feelings. (Contains 2 figures and 2 tables.)