In this report, we compile summaries of the biology of nine very large constrictor species and consider what effects these species might have on the ecology, economy, and domestic tranquility of the United States were such snakes to become established. Representatives of each group have been discovered in the wild in Florida, though evidence of reproduction is presently available for only three species, the Burmese Python (Python molurus bivittatus), the Northern African Python (Python sebae), and the Boa Constrictor (Boa constrictor). The occurrence of these three large constrictors in the wild in the same area of Florida may be a coincidence, but southern Florida has a climate that may be suitable for all of the giant constrictors and much of the commercial trade in giant constrictors passes through southern Florida. Thus the probability of exotic species establishment is greater in south Florida, though not limited to it. For each of the nine giant constrictor species under consideration, we review their climate tolerances and the areas of the country at risk (see section 10.2 in each of the species accounts: chapters Four-Nine). However, because we have established populations in south Florida, our geographic focus will always include Florida.