This document summarizes the proceedings of the Third Meeting of the Working Group on Performance Standards and Grid Code (WGPG-3) held in Ha Noi, Viet Nam on 3-4 June 2013. The meeting focused on (i) the gap analysis reports submitted by each Greater Mekong Subregion (GMS) country as well as the gap analysis report prepared for the Lao People's Democratic Republic, Cambodia, and Myanmar; (ii) Progress of Harmonization of Technical Standard Codes and Guidelines in the Area of Planning and Design, System Operation and Maintenance for the ASEAN Power Grid; (iii) Review of Proposed Guidelines for Technical Performance; (iv) TOR for Transmission Regulation and TOR for Metering; and (v) the next steps for the WGPG.