The purposes of this study were to examine the relationship between social skills and loneliness, and to contribute to prevention and intervention of loneliness in junior high school students. Questionnaires were administered to 83 students (45 males and 38 females). Correlation analysis showed that loneliness score was negatively related to the scores of peer reinforcement, social initiation, conflict resolution and assertion skills, and also positively related to the score of withdrawal behaviors. In addition, this study found gender differences in the role of social skills and problem behaviors on loneliness. Boys' loneliness was negatively related to peer reinforcement, social initiation, and assertion skills, and girls' loneliness was negatively related to conflict resolution skills, whereas both boys' and girls' loneliness were associated with withdrawal behaviors. These findings were discussed in terms of the context of social skills training.