SIMQUEST is an authoring tool for the design and delivery of simulation-based discovery learning environments, which can model the learning environments of a process, a procedure, or equipment. The learning process is interactive. For example, working in a simulation, learners can ask for extra explanations of phenomena, or for assignments. Additionally SimQuest users can create learning environments without programming or specific pedagogical knowledge. Creating learning environment is simple: based on a building-block approach, the teacher can insert these building blocks from a library into an environment. The environment can be edited (specialized) by adapting the building block properties and filling them with domain information. Building blocks include templates for simulation models, and interfaces for instructional support. SIMQUEST has a number of unique features: -SimQuest is a unique authoring tool that combines simulation tools with tools that help with structure learning through discovery. -Operation and manipulation of simulations are controlled by pedagogical measures (assignments, enabling conditions, progression levels). -Standard and tailor-made applications can be easily adjusted to suit the specific needs of teachers and students. Applications can be maintained very easily. -Simulations can vary from relatively simple to very complicated, be designed using pre-defined models from a library or models of their own making. Models can be used and re-used in applications for different targets groups on different levels. -Simulations that were not built with SimQuest can be integrated in a SimQuest-application and they can be brought under the control of the pedagogical environment. -Drag-and-drop design simplicity for tools and templates onto the canvas and a wide range of functional editors is available within the authoring environment, both oriented to the simulation kernel (model, interface) as well as to the pedagogical measures (assignments, explanations, monitoring). -An extensive step-by-step help wizard, a pedagogical advice system that presents information (and background) on discovery learning and also an extensive array of examples.