Two alternate explanations of loneliness by Weiss (1973), the situational theory and the characterological theory, were tested in a sample of 112 boys and girls between the ages of 12 to 14. In addition to responding to the Revised UCLA Loneliness Scale, participants completed instruments measuring variables linked to either the situational or the characterological explanations of loneliness. Using hierarchical analysis of sets, the results indicated that the set of variables used to test the situational theory explained more variance in loneliness when entered first (62%) or second (34%) in the analysis than did the characterological set when entered first (33%) or second (5%) in the analysis. The findings suggested that the situational explanation played a more significant role than the characterological explanation in understanding loneliness in early adolescents.