The paper reviews the planning and execution of the Gemini completion activities and the subsea system installation from the Ocean Star semi submersible drilling rig. The completion philosophy and design, including wellbore preparation, perforating, gravel packing, completion string design, and well flow and clean up, are discussed. The installation operations include the manifold, trees, 12" jumpers, and 4" jumpers.This paper describes the rig and equipment modifications implemented to provide clear access for the 4-slot manifold and trees, maximize the benefits of simultaneous operation, and optimize the completion installation. The modifications, combined with jointly developed procedures, enhanced the overall safety on the jumper installations simultaneous with drilling/completion operations.The paper provides details of the installation of the subsea trees and the completions. This includes the deployment of the multiplexed Electro/Hydraulic Installation/Work Over Control System (E/H IWOCS) and the inaugural running of the Enhanced Direct Hydraulic ( E-D-H) Schlumberger SenTree 7 subsea test tree.The paper includes an overview of the operation scheduling issues including the identification of primary and secondary simultaneous operation windows.