The projected rate of development obviously exceeded the capacity of the existing staff of curators and preparators, but it seemed unlikely that the workload would continue after Mission 66. The Museum Branch therefore decided to avoid building up a large force that would have to be cut back when Mission 66 ended. It would limit expansion as far as possible to the number of positions it would then need to service the increased number of park museums and take care of normal growth.46 Meanwhile it would augment production when necessary by contracting for exhibit preparation, a method the laboratory had used sparingly.

Before work could proceed on any Mission 66 exhibits, their planning demanded immediate attention. With the successful application of a team approach at Grand Canyon fresh in mind the branch acted quickly to organize three exhibit planning teams, each composed of a curator and a designer. The curator would have the academic background to wrestle with the complexities of subject matter, sort out the significant ideas, and express them in simple language. He would also have firsthand knowledge of visitor behavior in parks based on solid experience as an interpreter, or at least comparable knowledge from work in a museum. The designer would contribute mastery of form and color but also add important insights into content and communicative strategies. The team would spend enough time in a park to become familiar with its features and constraints as well as to obtain the input of the local staff. Frank Buffmire had already developed a format for exhibit plans that gave a park superintendent and other reviewers a clear picture of what the proposed exhibits would look like and say. It matched the park master plan in sheet size and contained a large colored sketch of each case and panel along with complete content specifications including label copy.

The three exhibit planning teams, referred to as the eastern, western, and history teams without circumscribing their scope by these titles, began work even before completely staffed. Robert L. Barrel and Myron D. Sutton, both experienced and articulate park naturalists, entered on duty in March 1956 as the curatorial members of the western and eastern teams respectively. At the same time the branch borrowed temporarily Albert C. Manucy, the scholarly and versatile park historian at Castillo de San Marcos National Monument, as curator for the history team. Before returning to his park in October he made outstanding contributions to four exhibit plans, including two particularly sensitive ones. Sutton received a design partner for the eastern team in April when the branch succeeded in recruiting Edward J. Bierly, a talented artist who specialized in wildlife subjects. The laboratory lent designers to the other two teams. Russell Hendrickson collaborated with Barrel on the western team's first job, then worked with Manucy to finish one important plan. Floyd LaFayette joined Barrel for the next two western ones. In June the branch hired a new designer, Hiram R. Haggett, for the history team. All three teams attacked their assignments with skill, imagination, and energy. Each submitted its first completed plan in May and started on the next without slackening pace.47 They would continue to function admirably through various changes in personnel until they had met the exhibit planning needs of Mission 66.

Work on an exhibit planning team made severe demands. It entailed much time in the field and pressure to keep up with construction schedules. The teams were expected to propose exhibits of endless variety and originality while maintaining existing standards that tended to limit change. Not surprisingly, planners came and went. Alan E. Kent, curator of photographic collections at the Wisconsin State Historical Society, took over Manucy's post with the history team in December 1956. After about five years he was promoted to a supervisory position in the Museum Branch. Following a reorganization in 1964 he went on to exercise intellectual leadership of Service-wide interpretive planning. A veteran park historian, John F. Luzader, took his place with the team for the remainder of the Mission 66 program. Haggett left the history team in August 1958 for a curatorship at the United States Air Force Museum under development at Dayton, Ohio. As his replacement Kent welcomed Daniel D. Feaser, promoted from an exhibit preparation position in the laboratory. A wildlife painter with excellent design sense, Feaser served ably with Kent and then Luzader until the team's work was finished.

The eastern team, which addressed its assignments with a constructively critical stance toward accepted practice, had Bierly as the design member throughout the program. Sutton became an instructor at the Service's new intake training center in August 1959. Marc Sagan from the Grand Canyon naturalist staff succeeded him in October and worked with Bierly until transferring to Region One in February 1962. He was followed by Earl W. Estes, park naturalist at Mount Rainier. Estes helped tackle some important historical as well as natural history plans including one for Appomattox Court House, which had to be fitted into a reconstructed building that provided far from ideal museum space.

Robert Barrel transferred the base of operations for the western team to San Francisco in August 1956 in preparation for reestablishing a western museum laboratory. He worked with borrowed designers, as noted above, until the appointment of John W. Jenkins that October. Barrel and Jenkins collaborated on the difficult plan for the Quarry visitor center at Dinosaur National Monument before the new laboratory demanded Jenkins' full attention. Raymond S. Price, who joined the laboratory in Washington as a preparator in November 1956, followed Jenkins as the western team designer in May 1957. Like Sutton, Barrel received a tempting offer in August 1959 and left to become naturalist for Hawaii National Park. Leland J. Abel, an archeologist serving as Region Four curator in San Francisco, replaced him promptly. Because of an extended special assignment that earned a unit award, the Abel-Price team could not keep up with needed exhibit plans, and Jenkins hired another designer, Herbert F. Martin, in July 1961. After Abel transferred to a park archeologist position in February 1962, Jenkins recruited two planning curators as replacements: Paul F. Spangle, a naturalist, and Gilbert R. Wenger, an archeologist. This gave the western laboratory two teams, Price and Martin pairing interchangeably with Spangle and Wenger. Even their best efforts could not meet the workload in the later years of Mission 66, and Jenkins obtained two more exhibit designers: Gerald Ober from the Jefferson National Expansion Memorial in January 1963 and David Ichelson from his position as laboratory shop supervisor that October.