As the thrust of the study is upland development with greater sensitivity to the underlying causes of change, this examines in detail the extent of population pressure in Philippine upland communities with respect to the conditions affecting population growth, including the broader elements of demographic stress and the corresponding adaptive changes of upland communities. Specifically, it estimates the current population in the uplands using census data and determines the extent of migration to upland areas. It also analyzes the socioeconomic and environmental determinants of frontier migration and evaluates through case studies the dynamics of migration behavior and the effects of socioeconomic and environmental factors influencing population movements.