This study sought to describe the emergent interaction system of letterboxing in North America. Letterboxing is a hobby that can trace its roots to treasure hunting and orienteering. A letterbox is a container holding a logbook and carved rubber stamp found by following clues. Participants use the stamp to make an imprint in their personal journal, and in turn, they record their personal stamp and a message in the letterbox's logbook. Letterboxing has been growing rapidly in North America since its start in 1998; currently 21,498 letterbox clues are listed on just one of the hobby's largest websites. I recruited 355 participants for this study through invitations on websites used by letterboxers. I conducted the research using a combination of descriptive qualitative methods and qualitative analysis of data from three open-ended questions gathered on an online survey instrument. I designed survey items to gather data that described the participants and their behaviors including demographics, participation activities, and communication activities. I then analyzed these data using frequencies, percentages, and cross tabulations. Participants in the study were predominantly white, female, under the age of 50 and educated. I used content analysis of survey data obtained through open-ended questions to identify impetus, motivation, and emergent behaviors. The impetus for participation varies from hearing about it from a friend or relative to publications and broadcasts. Others stumbled across letterboxing via Internet searches or by finding a letterbox in the woods unintentionally. The "thrill of the hunt," hiking, and a love of the outdoors are primary motivations for participation. Made possible by the interconnectivity of the Internet, an informal collective has emerged that embraces individual variants and claims it for its own in an online learning community. Community activities such as gatherings, web rings, talk lists, discussion boards, and postal letterboxing bring participants together, increase engagement, and build community around similar interests. Collaborative innovations, or emergent interactions of participants, create new forms of letterboxing and lead to experimentation, probing, learning, and enhancement of individual experience. A model of emergent interaction is presented in the conclusion section. / Department of Educational Studies