This paper presents the concurrent Engineer-To-Order (ETO) concept. ETO is a Make-To-Order operation that starts with a product specification and finishes with delivery of a customised product. By synchronising the production activities in a product development process, a concurrent ETO operation can effectively improve and assure the product development lead time. This paper defines its relevance to other contemporary manufacturing operation concepts and proposes a concurrent ETO operation framework. It details the interactions among the sales, production, engineering, and manufacturing operations with a focus on hierarchical planning, incremental scheduling, and operation control.