Ecotourism and protected area visitation have been steadily increasing in recent years in Central and South America, inevitably resulting in natural resource impacts. The consequences of such impacts may include natural resource degradation, diminished aesthetic qualities, or decreased functionality of certain facilities like recreation sites and trails. Recreation ecology and visitor impact management expertise and tools are available to help balance the potentially conflicting management goals of protecting natural resources and permitting visitation but such knowledge has not been widely used in Central and South America. The goals of this research were to characterize certain visitor-related natural resource impacts and to determine how these impacts could be assessed and managed in Central and South America. The research included case studies of eight protected areas in Costa Rica and Belize, trail impact assessment research at Torres del Paine National Park in Chile, and development of a new visitor impact assessment and management framework, presented as three papers intended for journal submission. The first paper had two objectives: 1) to identify visitor-related natural resource impacts at selected protected areas in Costa Rica and Belize to increase awareness about visitor impact problems, and 2) to apply and compare rapid trail and recreation site impact assessment procedures to provide study site managers with impact data and impact assessment procedures. A variety of natural resource impacts were reported by interview subjects and recorded by rapid assessment procedures. The management utility of the rapid trail and recreation site impact assessment procedures were compared and discussed and the need for developing additional rapid assessment procedures to evaluate other resource impacts reported by protected area managers was also identified. The intent of the second paper was to investigate trail impacts at Torres del Paine National Park. Study objectives included measuring the frequency and magnitude of selected trail impacts, and comparing the relative impact contribution of the amount of use, vegetation type, trail position and trail grade on common condition indicators such as width and incision. Findings somewhat contradicted those of other studies, revealing that amount of use significantly contributed to trail width and incision. However, findings also indicated that vegetation type and trail grade contributed to number of informal trails and trail incision, respectively. A variety of management strategies were recommended and suggestions were provided for future monitoring studies. The purpose of the third paper was to propose a new visitor impact assessment and management framework that would provide managers with a feasible means of addressing visitor impact management concerns for selected protected areas in Central and South America. The Protected Areas Impact Assessment and Management (PAIAM) framework was adapted from existing frameworks like carrying capacity and the Limits of Acceptable Change to provide a simple, cost-effective and relatively quick decision making process. PAIAM analyzes visitor impacts using an expert panel and incorporates stakeholders and local residents into decision making. This study experimentally applied the new framework in Mexico and compared PAIAM to existing frameworks. The focus of this dissertation is on Central and South America since they are heavily visited ecotourist regions that could potentially benefit from applying recreation ecology and visitor impact expertise and tools to protected area management. This research demonstrated that a variety of visitor impacts are affecting natural resources and visitor facilities like trails and recreation sites at selected protected areas in Central and South America. This research also developed and applied rapid impact assessment procedures and visitor impact frameworks for use in Central and South American protected areas. / Ph. D.