spontaneous colonization may occur in remote developing country areas under harsh conditions without government assistance while official colonization schemes often fail to attract and retain settlers. this study tour report, based on a review of available literature and government statistics and on interviews with local officials, faculty members, and farmers, examines spontaneous colonization at four south american sites - tingo maria and san juan del oro in peru, and itapua and alto parana in paraguay. in contrasting colonization in these four settings, the author notes the importance of roads and transportation in stimulating colonization, as well as the amount and quality of available land, especially for large-scale, commercial farming of highly profitable, export-oriented crops (e.g., coffee, cotton, soybeans). population pressures, however, may lead to colonization far from existing roads (up to a 4-day walk) and in very marginal lands. although the availability of public services is not unimportant, colonists will settle beyond their reach