This paper presents a framework to interactively control avatars in remote environments. The system, called AMITIES, serves as the central component that connects people controlling avatars (inhabiters), various manifestations of these avatars (surrogates), and people interacting with these avatars (participants). A multiserver–client architecture, based on a low-demand network protocol, connects the participant environment(s), the inhabiter station(s), and the avatars. A human-in-the-loop metaphor provides an interface for remote operation, with support for multiple inhabiters, multiple avatars, and multiple participants. Custom animation blending routines and a gesture-based interface provide inhabiters with an intuitive avatar control paradigm. This gesture control is enhanced by genres of program-controlled behaviors that can be triggered by events or inhabiter choices for individual or groups of avatars. This mixed (agency and gesture-based) control paradigm reduces the cognitive and physical loads on the inhabiter while supporting natural bidirectional conversation between participants and the virtual characters or avatar counterparts, including ones with physical manifestations, for example, robotic surrogates. The associated system affords the delivery of personalized experiences that adapt to the actions and interactions of individual users, while staying true to each virtual character's personality and backstory. In addition to its avatar control paradigm, AMITIES provides processes for character and scenario development, testing, and refinement. It also has integrated capabilities for session recording and event tagging, along with automated tools for reflection and after-action review. We demonstrate effectiveness by describing an instantiation of AMITIES, called TeachLivE, that is widely used by colleges of education to prepare new teachers and provide continuing professional development to existing teachers. Finally, we show the system's flexibility by describing a number of other diverse applications, and presenting plans to enhance capabilities and application areas.