Which nasa program practiced rendezvousing and docking in space?

Project Gemini, the program between the Mercury and Apollo missions, was conceived as as necessary stepping stone from initial rocket and orbital successes to further study weightlessness and effects on the Astronauts. It was also to test docking designs for the upcoming Apollo Command / Lunar Module docking operation prior to going to the Moon, and was also intended to practice rendezvousing and docking with other orbital platforms.