Many modeling languages share common concepts, such as types, expressions, statements, or literals. Nonetheless, these essential language concerns are often developed again and again, independently, and with minor changes here and there. A well-designed and extensible library of such, tried-and-tested, language components can facilitate engineering new languages through their reuse. We utilize the powerful language composition techniques of the MontiCore language workbench to conceive such a library, present its components, and their rationale. This fosters language engineering in MontiCore and can inspire more efficient language engineering in the technological spaces of other language workbenches.