The S4 Saturn rocket stage, manufactured by the Douglas Aircraft Space Division, is the first 'live' second stage to be utilized by NASA. This film details the production and testing highlights of the stage. Sections as follows: flyby footage of Douglas buildings, model of S4 stage; milling the tank section in a waffle pattern; forming the tank walls on a brake machine; explosive milling of the propellant tank segments; chemical milling of common dome segments; fabrication of forward and aft structural panels; dome construction, welding to bulkhead; assembly of S4 stage components - forward interstage, aft skirt, thrust structure, LOX tank baffle, aft interstage; installation and welding in assembly and calibration tower; test facility to study the characteristics of liquid hydrogen at -423 degrees Farenheit - surface behaviour test; testing of Saturn S4 stages at Douglas Sacramento Facility; liquid hydrogen storage tanks; liquid hydrogen characteristics testing tank - filling with liquid hydrogen, pressurizi