The son of Samuel E. and Irene Larsen Trueblood was born on May 4, 1916, in Kindred, North Dakota. He graduated from Kindred High School in 1932. He received a bachelor's degree with distinction from the University of Minnesota in 1937. In the same year he joined Badman, Finny & Co. He left the firm in 1942 to serve in the Navy during World War II. He was discharged in 1946 at which time he joined a firm which merged later into the firm now known as Touche Ross & Co. He was made partner in 1947, and elected as Chairman of the Board in 1963, the position he held at his death. He was certified as a CPA in 1941 (Illinois). In recognition of his performance on the CPA examination, he was awarded the AICPA's Elijah Watt Sells Silver Medal in 1941 and the Illinois Society of CPAs' Gold Medal.
He was active in professional organizations, serving as president (1965-66), and vice president (1962-63) of the AICPA. He served as president (1959-60) and vice president (1958-59) of the Pennsylvania Institute of CPAs. He also served on the AICPA's Council (1959-60), Executive Committee (1961-63, 1964-67; chairman 1965-66), the Executive Committee and APB (1963-65). He chaired its Committee on Long-Range Objectives (1961-65), Accountants International Study Group (1966-68), and the Study Group on the Objectives of Financial Statements (1971-73). The AICPA publication Objectives of Financial Statements (1973), is a report of the latter group. He also served on the Commission for the Study of the Common Body of Knowledge for CPAs (1963-66), whose recommendations appear in the AICPA publication, Horizons for a Profession (1967). He received the AICPA's Gold Medal Award (1971) and the Alpha Kappa Psi Foundation Accounting Award (1972). He held memberships in the AAA, NAA, Illinois Society of CPAs, and Institute of Internal Auditors.
He was actively involved in numerous government, civic, and community organizations, including membership on President Johnson's Commission on Budget Concepts (1967), as a consultant to the Assistant Secretary of the U. S. Air Force (1953- 61), as a councilman of Fox Chapel, Pennsylvania (1957-61), membership on the Board of Directors of the Civic Club of Allegheny County, Pennsylvania (1951-60), and on the Visiting Nurses Association of Allegheny County (1957-61).
He took a sabbatical and did research and lecturing as Visiting Ford Distinguished Research Professor at Carnegie-Mellon University (1960-61). He also lectured at Stanford University (1969), University of Chicago (1971), and Oxford University (summer, 1967). He was a long-time Chairman of the Advisory Council, Institute of Professional Accounting at the University of Chicago (1964-74). He urged his fellow CPAs to adopt statistical sampling in the profession.
A frequent author for professional journals, he authored the following books: Sampling Techniques in Accounting with Richard M. Cyert, The Future of Accounting Education with George L. Bach and Justin Davidson (1961), Auditing, Management Games, and Accounting Education with Neil Churchill and Merton Miller (1964), and William W Werntz: His Accounting Thought with George H. Sorter (1968).
In 1963 the Board of Trustees of the University of Minnesota honored him with an award for his outstanding achievements; in the same year he was elected to honorary membership in the University of Minnesota Beta Alpha Psi chapter. He was also a member of Beta Gamma Sigma. An accounting chair in his name was established at Carnegie-Mellon University. After his death, the Touche Ross Foundation established the annual Robert M. Trueblood Memorial Professors Seminars in collaboration with the AAA. During his lifetime, he had started a firm program of such seminars in order to increase dialog between the practicing profession and academia.
He married Florence Henry on November 30, 1940; they had two children. He enjoyed music; in his youth, he was well on his way to becoming a concert pianist before giving it up for a career in accounting. He died on February 7, 1974 at the age of 57.