Formal specification has become increasingly important in software engineering, both as a design tool, and as a basis for verified software design. Formal methods have long been in use in the field of programming language design and implementation, and many formalisms, in both the syntactic and semantic domains, have evolved for this purpose. In this thesis we examine the possibilities of integrating specifications written in different formalisms used in the description of programming languages within a single framework. We suggest that the theory of institutions provides a suitable background for such integration, and we develop descriptions of several formalisms within this framework. While we do not merge the formalisms themselves, we see that it is possible to relate modules from specifications in each of them, and this is demonstrated in a small example.