The 19,100 kg (42,000 lbm) Russian service module Zvezda (Russian for "star") will provide crew quarters, propulsion and flight control for the International Space Station. Zvezda will assume control of the station, taking over attitude control and reboost of the station. Computers on Zvezda will also handle guidance and navigation of the station. As the station grows, new modules will take over roles initially handled by Zvezda. However, Zvezda will remain as the core of the Russian contribution to the station. Zvezda includes two docking ports for future Russian modules to attach to the station, in addition to the docking port to be used by Soyuz and unmanned Progress cargo spacecraft.

The Service Module consists of three pressurized compartments: a small, spherical Transfer Compartment at the forward end; the long, cylindrical main Work Compartment; and the small, cylindrical Transfer Chamber at the aft end. An unpressurized Assembly Compartment is wrapped around the exterior of the Transfer Chamber at the aft of the module. The Assembly Compartment holds external equipment such as propellant tanks, thrusters and communications antennas.

The Service Module includes four berthing ports, one in the aft Transfer Chamber and three in the spherical forward Transfer Compartment, one facing forward, one facing up and one facing down. The aft docking port has a probe and cone docking mechanism to allow dockings by Progress resupply spacecraft and Soyuz piloted spacecraft. It also will be outfitted with an automated rendezvous and docking system