Twitter may be useful for learning about indoor tanning behavior and attitudes. The objective of this study was to analyze the content of tweets about indoor tanning to determine the extent to which tweets are posted by people who tan, and to characterize the topics of tweets. We extracted 4,691 unique tweets from Twitter using the terms "tanning bed" or "tanning salon" over 7 days in March 2016. We content analyzed a random selection of 1,000 tweets, double-coding 20% of tweets (κ = 0.74, 81% agreement). Most tweets (71%) were by tanners (n = 699 individuals) and included tweets expressing positive sentiment about tanning (57%), and reports of a negative tanning experience (17%), burning (15%), or sleeping in a tanning bed (9%). Four percent of tweets were by tanning salon employees. Tweets posted by people unlikely to be tanners (15%) included tweets mocking tanners (71%) and health warnings (29%). The term "tanning bed" had higher precision for identifying individuals who engage in indoor tanning than "tanning salon"; 77% versus 45% of tweets captured by these search terms were by individuals who engaged in indoor tanning, respectively. Extrapolating to the full data set of 4,691 tweets, findings suggest that an average of 468 individuals who engage in indoor tanning can be identified by their tweets per day. The majority of tweets were from tanners and included reports of especially risky habits (e.g., burning, falling asleep). Twitter provides opportunity to identify indoor tanners and examine conversations about indoor tanning.