(1) A procurement or project delivery arrangement whereby a single entity (a contractor with subconsultants, or team of contractors and engineers, often with subconsultants) is entrusted with both design and construction of a project. This contrasts with traditional procurement, where one contract is bid for the design phase and then a second contract is bid for the construction phase of the project.

(2) A project delivery method where a design-build contractor (contractor-led D-B), A/E design professional (design-led D-B), or CM (CM-led D-B) is directly responsible for both the total project design and construction of the project. Design-Build liability can be explicitly conveyed through the contract documents, or implicitly conveyed through the assumption of project-specific design liability, via performance specifications.

(3) A written agreement between and contractor and owner wherein the contractor agrees to provide both design and construction services.