This text deals with the interaction between Mercedarian missionaries and the indigenous Lenca Indian population of Western Honduras during the early 16th to mid-18th centuries. Using an anthropological perspective, it relies on ecclesiastical archival material in conjunction with preliminary archaeological evidence as an integral source of data. A description of the local processes of missionization in a frontier region examines the organization, operation and goals of the Mercedarian mission province located in the colonial Audiencia of Guatemala. Summary data concerning aspects of Lenca society and physical environment relevant to investigation of mission activities are provided.