The use of social and technological intermediaries to seek intimate partners has a long history. Yet the affordances and limitations of modern computer-mediated communication (CMC) systems built for this purpose--specifically, online dating sites--present new challenges and opportunities for those who use them to initiate intimate relationships. The sheer number of potential mates available on such sites is tremendous, but accurately gauging their appeal and suitability for a relationship can be difficult through CMC. This dissertation presents a longitudinal survey of users of a major U.S. online dating service as they interact with potential dates online, meet them in person, and in some cases establish intimate relationships. The survey addresses two research questions: how interpersonal perceptions change when online daters meet in person for the first time, and how online and offline perceptions are associated with relationship duration, satisfaction, and intimacy. With respect to the first research question, I find that on average measures of liking and willingness to enter into a romantic relationship decline after participants meet their dates face-to-face for the first time. This result held for both inexperienced and experienced online daters. With regard to the second research question, I find that participants' perceptions of their dates before they have met in person generally do not predict the duration of the subsequent relationship, if any. However, their perceptions on many dimensions shortly after meeting in person are significantly associated with relationship duration. At the same time, among those who do begin dating, perceptions on numerous dimensions both pre-meeting and post-meeting are associated with intimacy and, to a lesser degree, relationship satisfaction in the weeks after the first date. That is, it appears that initial judgments from online interaction do not predict whether a couple will form a relationship, but these judgments do predict metrics of relationship quality if they choose to do so. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]