This paper focuses on the interaction between the president and the prime minister, outlining the details of the internal workings of the executive, based on the variables of whether the president and the prime minister ”compete” for executive power or rationally ”yield” executive power. By examining the cases of countries with semi-presidential systems, this paper aims to explain the implications and predict the potential direction of transition in various forms of semi-presidentialism. This paper seeks to demonstrate that a dual-executive inherent in semi-presidentialism, as well as the competition/cooperation between the president and the prime minister, are the most important factors determining how semi-presidentialism operates.