This paper describes the U.S. Space Station launch and assembly sequence and the mission support capabilities available in man-tended and permanently manned modes. Design and operational constraints affecting launch package configurations and orbital deployment and assembly are defined. The resulting flight configurations and associated payload accommodations are described with emphasis on the early flights through man-tended capability. The initial mission objectives will emphasize engineering data collection (structural, thermal, power, control, propulsion, etc.) to verify design and to calibrate system models and simulation tools. On-board information will be used to characterize the microgravity, electromagnetic, particulate, and other environmental features for the benefit of Space Station users. Early flight configurations will provide accommodation for attached payloads which may include experimentation in materials exposure, solar physics, and Earth and stellar observations. These mission payloads, once installed and initialized by the Shuttle flight crews, will be operated by ground control from their mission specialists. When the pressurized laboratory is added, the mission emphasis will shift to microgravity experimentation including material processing and manufacturing research, life sciences, and supporting technology research and development. These missions will be operated in a man-tended mode. Installation, real-time operation, and servicing will be performed by Shuttle during periodic visits; a combination of ground control and automatic modes will be used between Shuttle flights. As Station build-up continues, resources available for payloads will also increase. With the achievement of the permanently manned capability, continuous crew support will be available for mission activities. This paper summarizes each step of this build-up process and the capabilities available for Station operation and payload activities versus time.