In software engineering reference models are used as a guidance for implementing potential solutions to recurring problems, e.g., as reference architecture models or reference data models. Despite the broad use of reference models in practice, there is no clear definition for what it means that a concrete model conforms to a reference model. This prevents us from developing automated tools for conformance checking. In this paper, we provide a semantically useful definition of conformance of concrete models to reference models. We then present concepts and tools for concrete automated conformance checks for (1) class diagrams, (2) feature diagrams, and (3) state charts, which we developed based on that definition. Finally, we discuss (1) the commonalities and differences of the presented automated conformance checks and (2) general design considerations for developing reference model conformance checkers in the context of model-driven engineering. Key findings are that reference models should use the same language as their concrete models, conformance checks require conformance mappings between reference and concrete model elements, and conformance rules must be based on formally defined language semantics.