This study examined the sex differences in reports of social support (network size and satisfaction), loneliness, and depression among Korean college students and examined whether measures of social support and loneliness predicted depression scores. In the sample were 452 college students enrolled in four universities in Korea. The women reported a larger social support network size and being less satisfied with their support than the men. Women reported higher scores on the Revised UCLA Loneliness Scale and the Beck Depression Inventory than men. Social support satisfaction scores and network size on the Social Support Questionnaire-6 and scores on the Loneliness Scale predicted scores on Depression in both the groups. Loneliness was the largest predictor of Depression for either sex. The amount of variance in Depression accounted for by Loneliness was 35% for women and 24% for men.