Due to recent increases in chip complexity, behavioral synthesis has become an important area of research and company interest. However, there has been market resistance to the automatic behavioral synthesis approach for two reasons. It often produces results inferior to manual designs, and it allows only minimal user control. To overcome these hurdles, we present a design methodology for human interaction in design synthesis, which, in contrast to the automatic synthesis approach, gives the human designer fine-grain control over synthesis tasks, and continually supplies feedback in the form of quality measures so that the user can make informed design-related decisions. To confirm the feasibility of the proposed design methodology and to demonstrate its power and flexibility, we also present the Interactive Synthesis Environment (ISE), a working software environment comprising design views, quality measure feedback, and synthesis algorithms.