Transactional distance theory predicts an inverse relationship between dialogue and structure in an educational transaction. It is a powerful theory, but it is inherently fuzzy in formulation and may have exceptions. This article reinterprets the theory as one of transactional control, where the central issue is one of choices and who makes them. The article discusses a class of computer-based educational environments that anomalously seem to combine both high dialogue and high structure, providing the learner with both high and low degrees of constraint simultaneously. In these environments the behavior of users causes structural change, which in turn causes changes in the behavior of users. Such processes are a form of stigmergy, a word originally used to describe this effect in termites, where it coordinates the formation of termite mounds. Stigmergy in an e-learning environment can enable a self-organized structure to arise out of dialogue, simultaneously providing both high and low transactional distance/control. Environments built this way may be very flexible learning spaces. A number of exemplars embodying the principle are described, followed by an exploration of unresolved issues and directions for future research. (Contains 3 figures.)