The aim of this article is to identify content-related features of the most retweeted messages posted by Spanish and non-Spanish book publishers on Twitter. A content analysis has been conducted to identify the topic of the tweets and whether they include book title hashtags, images and hyperlinks, and if so, what the images are about and where the links point to. As a complement, a word association analysis has been carried out to determine which terms are associated with each of the different publishers. Overall, publishers tend to tweet about themselves and their books for marketing purposes. About half of the publishers have Twitter accounts. Spanish publishers’ tweets often contain literary quotes, while the top tweets by non-Spanish publishers are more likely to contain free prize draws. Publishers seeking to engage with potential readers on Twitter could consider quotes and giveaways to build their audience, in addition to tagging author @usernames in book-related posts to help reach the author’s network.