Prior work suggests that for older adults, using the Internet may reduce loneliness and thereby improve mental health. However, most studies concentrate on the relationship between Internet use and depression. Anxiety as an outcome of interest remains less understood, particularly for older adults. Using data from an online survey of older adults age 60+, we examine the relationship between varying ways of socializing online and general anxiety. Differing from past work, we employ use measures that focus on experiences with online social interaction in general rather than restricting these to particular platforms. We find that belonging to online communities and participating in meaningful online discussions are associated with greater anxiety. Participation in meaningful online discussions specifically about health and aging also relate to greater anxiety. Our results suggest a relationship between greater amounts of online social interaction and diminished mental health among older adults.