A growing number of manufacturing companies are treating sustainability as a strategic objective that will increase both their global competitiveness and their market share. To implement this objective, these companies must first assess, and then evaluate, their current sustainability performance. Assessments and evaluations are carried out by choosing among a variety of existing sustainability metrics, assessment tools, and related standards. To help companies make the best choice, the National Institute of Standards and Technology is establishing a Smart Manufacturing Testbed, with an initial emphasis on sustainable manufacturing. The sustainable manufacturing testbed will provide (1) the infrastructure to demonstrate, test, and validate assessment methods and tools; (2) the ability to test conformance to current and future assessment-related standards; (3) the capability needed by the manufacturing industries to perform sustainability assessments; and (4) a repository for storing sustainability data related to products, resources, and processes from case studies describing real manufacturing scenarios. This article summarizes testbed requirements and functions, proposes an architecture that meets those requirements and implements those functions, and introduces a prototype system that enables companies to use the testbed.