Articles 31 and 32 of the Vienna Convention on the Law of Treaties constitute the applicable law for interpreting investment treaties. Investor-State arbitrations have shown that application of these provisions can be problematic. This article identifies key problems in Articles 31 and 32 and poses the following three solutions: the use of a treaty interpretation schedule to be completed by each party in relation to a disputed interpretation of an investment treaty (much like a Redfern Schedule), the formulation of guidelines to assist interpreters to understand best practice in the application of the Convention’s interpretation rules, and the adoption of approaches formulated by behavioural scientists that may contribute to treaty interpretations becoming wiser.