ABSTRACT. Like the North American frontier, Ecuador's Amazonian margin has advanced in periodic waves. But the impetus has been extremely varied, interlacing periods of socioeconomic crisis with times of prosperity. Recent events in eastern Ecuador confirm that urbanization is a fundamental component of frontier development in South America. The urbanization process is not a sign, however, of regional economic strength. Capital gains at the periphery are transferred to the nation's core region. Even the larger boom towns display little functional specialization; they are, instead, precariously dependent on employment in the public-service sector. Nonetheless, urban centers in the Ecuadorian Amazon continue to grow and to drain surrounding rural areas of younger and more educated individuals.