Social media have been increasingly used by sports organizations to communicate with the public. This study explored the Twitter-using practices of National Basketball Association (NBA) clubs (N = 30) in the U.S. in building relationships with their fans during the 2013–14 season. Specifically, it focused on how these clubs used Twitter to build professional, personal, and community relationships through a content analysis of 5,561 tweets on their official Twitter sites. The results suggested that NBA clubs tended to use social media to develop professional relationships with their publics via sharing information and promoting products. There were significant relationships between relationship dimensions and the number of retweets and favorites from Twitter followers. Sports organizations should use social media effectively to strengthen the professional, personal, and community relationships with their publics.