William Turnbull, Jr. continued the California office of MLTW/Moore, Turnbull which in 1984 became William Turnbull Associates still located at Pier 1 1/2 in San Francisco. With a staff of thirty, William Turnbull Associates has designed buildings located across the country and received more than eighty design awards. Turnbull specialized in designing projects on difficult or sensitive sites, such as Foothill Student Housing at the University of California, Berkeley. He has lectured throughout the United States and Canada, taught at Stanford University, and acted as visiting critic at the Massachusetts Institute of Technology, Yale University, the University of Maryland, and University of California, Berkeley. Turnbull was also a member of the University of California, San Diego's Design Review Board and was on the editorial Board of Architecture, California. Turnbull was a Fellow of the American Institute of Architects. He illustrated The Place of Houses and co-authored The Poetics of Gardens (with Moore and Mitchell). He authored the Global Architecture MLTW/Charles Moore, William Turnbull., The Sea Ranch, California 1966-.
Beginning in 1977, Turnbull divided his time between architecture in San Francisco and wine making at the Johnson Turnbull Vineyards in Napa Valley, producing more than six thousand cases annually. The Sea Ranch Affordable Housing element of the California Coastal Plan for The Sea Ranch was conceived as a response to the recognized future need for affordable housing for future employees of an expanded Sea Ranch Lodge and Village. The initial fifteen units were designed by noted architect William Turnbull, one of the "founding architects" of The Sea Ranch. The element as a whole, in addition to particular designs, received numerous architectural awards.
Turnbull, along with Charles Moore, Lawrence Halprin, and Donlyn Lyndon, has again participated in planning and design at The Sea Ranch. Turnbull completed his work on the Affordable Housing element at The Sea Ranch with the addition of thirty-five new units. Moore, Lyndon, and Halprin have completed the planning and initial design work on the expansion of The Sea Ranch Lodge and Village. Since Moore's passing in the early 90's, Lyndon and Halprin have continued this work, hopefully to completion in 2002.
Some of Turnbull's Sea Ranch homes available as vacation rentals are the White Fir Cottage and the Barnacle house.