This chapter examines how Nigeria’s legislature and executive interact and check each other in a manner that prevents the abuse of powers. Section 1 provides a general introduction. Section 2 focuses on the constitutional role of the legislature and the executive. Section 3 examines the features of Nigeria’s presidential system. Section 4 explores the areas of interaction between the legislature and the executive in the discharge of their constitutional roles. Section 5 discusses the causes of legislative–executive conflicts and their impact on good governance while Section 6 concludes. The chapter argues that although the constitution makes ample provisions for a clear separation of powers between the legislature, executive, and the judiciary as well as providing for checks and balances to guide the relationship between the three branches of government, democratic principles have not been fully embraced due to the military culture existing between 1966 and 1999.