We aimed to explore conversations about mental health difficulties by Reddit users who posted within college subreddits during the COVID-19 pandemic. Data were collected from the subreddits of 22 California campuses, representing 113,579 anonymous members. Using the following search terms, we retrieved 577 posts (ie, 268 original posts and 309 replies): COVID, Coronavirus, Quarantine, Pandemic, Anxiety, Anxious, Depressed, Depression, Overwhelmed, Stress, and Stressed. We used inductive, thematic data analysis to explore themes within posts and replies dated from 3/16/2020 to 3/16/2021. We identified the following themes: 1) the COVID-19 pandemic has negatively impacted engagement with learning; 2) remote learning has exacerbated students' mental health difficulties; and 3) students provide and receive social support online. These findings have implications that are particularly relevant as campuses are faced with continuous decisions related to repopulation.