Background: An essential component of new relationship development is sexual communication between partners. The rise of technology has allowed couples to use text messaging to facilitate these conversations. The current study examines how emerging adults (18–25 years) in new relationships communicate about sex through text messages. Methods: We conducted inductive thematic analyses of text messages between different-gender couples in the first six months of their relationship (20 couples, N = 40) in which the women were between 18 and 25 years of age. We used the Dedoose qualitative analysis software and a coding team of 16 coders. Reliability was established through the “test” function of Dedoose, with codes of Kappas less than 0.70 discussed and refined in the codebook. Results: Primary themes of how couples communicate about sex emerged, which included the use of humor, discussing previous sexual experiences and partners, and sharing interests around future sexual encounters. During thematic analyses, secondary themes of motivations for sexual communication emerged, including learning, bonding, and enhancement. Conclusions: Addressing the varied motivations emerging adult couples may use in text messages can be leveraged for improving sexual health. Theories related to relationship development may not fully capture how couples discuss sex, particularly via text messages.