Juridical acts are drafted in order to create legal effects. Giving effect is, however, not always as easy as it might seem at first sight. During the execution of the juridical act, it frequently is unclear which obligations it actually entails. This lack of clarity results from the fact that juridical acts are concluded using a code, which is language. Because of the vagueness of expression or as a result of the indistinctness of language, the uttered intention is not always in agreement with the real one. Sometimes an expression has more than one meaning. Besides, words are never clear. They derive their meaning from a context. Therefore all communication, including every juridical act, needs to be interpreted. This PhD investigates the interpretation of juridical acts. All juridical acts volitional acts. Therefore, the governing interpretation criterion has to be the intention. When it comes to unilateral acts, the intention is the will of the party who undertakes a performance. When it comes to reciprocal acts, the intention is the common will of the contracting parties. Two different approaches can govern the search for the intention. One the one hand, one can argue that the real intention has to be decisive. A contract comes into being as a result of a consensus, and intention is also the base of every unilateral juridical act. On the other hand, one can reason that the written word is of overriding importance. It is the outward reflection of the intention, which the other party and third parties have become acquainted with. In some jurisdictions, the essential rule of interpretation is subjective, while other jurisdictions start from the premise that interpretation has to be fundamentally objective. In practice, however, all interpretative systems use subjective as well as objective components. This finding of course triggers the question: which interpretative system is the best one? This PhD investigates what a coherent and practicable system of interpretation of jurdical acts should look like, taking into account the autonomy of the parties on the one hand and legal certainty on the other hand.