Conlanging, or the process by which someone creates a constructed language (conlang) has become more and more popular in recent decades. People create languages for a myriad of reasons, including cinema, books, videogames, role-playing campaigns, or even just for fun either as a side project or for personal use, or for real life functioning communication like Esperanto. The object of this paper is to study one of these fields in particular, that of conlanging for use in science fiction or fantasy books. It is easy for the conlangers (the people creating the languages) to be excited about their language, but my research question focuses on the readers. What expectations do readers have for conlangs in these books? After interviewing 8 avid science fiction and fantasy readers, and receiving 13 responses to a survey, I have discovered four major trends: 1) readers don’t want the languages to be overbearing—they enjoy simple conlangs that they can understand, 2) they want the language to serve some narrative purpose (be relevant to the plot), 3) they enjoy conlangs helping to name people and places, and 4) they want the conlangs to be well thought out (not to be shallow or just gibberish). Knowing that these are the priorities for readers of science fiction and fantasy will hopefully help authors in these genres to know how to best use their conlangs in their works.