Reification is a popular technique to reduce complexity of the software design process. This technique has to be re-investigated for the comprehensive object-oriented approach. Object-oriented specifications comprise structure and behavior of systems. Due to this sophisticated idea two kinds of reification appear: data reification and action reification. In this paper we present an approach to incorporate action reification in object-oriented specification. A logic is defined which serves as a domain to translate specifications. Moreover, we define a language for reification and formalize it with the logic. Interpretation structures of this logic are labelled event structures which are introduced briefly and satisfaction of formulas is defined. With an example we explain our ideas of correct reification and establish a reification condition. Finally, we show how data reification is uniformly included in our approach.