This paper examines how economic openness influences regional development in a developing country, with the Philippines as a case study. It first looks at the disparities in economic and social indicators across the country's 14 regions and over time. Metro Manila continues to tower over the national economic landscape, although economic dispersal especially in adjacent regions appears to be expanding. The paper then analyzes the determinants of regional development, using five-year panel data. Trade openness appears to be beneficial to regional economic growth and, via growth, poverty reduction. However, it cannot by itself be expected to bring about more balanced regional development.