Increasing the share of renewable power from variable sources, namely solar and wind energy, requires technological developments to be accompanied by well-designed regulations for grid management and operation. Grid connection codes for variable renewable energy (VRE) sources have evolved hand-in-hand with technological and operational practices, driving the adoption of the best available technologies for VRE grid integration. Lessons from pioneering countries can help in drafting a grid code for VRE integration. Yet national codes should not be appropriated wholesale from other countries. Precise technical requirements need to reflect local conditions, including the character of the existing power system. System size, voltage, interconnections, generation and distributions loads, the conventional energy mix, and the prevailing policies on renewable energy must all be taken into account. Codes must define the respective roles and responsibilities of the government and the grid operator, as well as set compliance verification mechanisms. IRENA’s report provides guidance for countries with ambitious VRE targets to develop grid codes that assure power system security.