[en] The Basis of Estimate Software Tool (BEST) was developed at the Rocky Flats Environmental Technology Site (Rocky Flats) to bridge the gap that exists in conventional project control systems between scheduled activities, their allocated or assigned resources, and the set of assumptions (basis of estimate) that correlate resources and activities. Having a documented and auditable basis of estimate (BOE) is necessary for budget validation, work scope analysis, change control, and a number of related management control functions. The uniqueness of BEST is demonstrated by the manner in which it responds to the diverse needs of the heavily regulated environmental workplace - containing many features not found in conventional off-the-shelf software products. However, even companies dealing in relatively unregulated work places will find many attractive features in BEST. This product will be of particular interest to current Government contractors and contractors preparing proposals that may require subsequent validation. 2 figs