He studied at the City College of New York and Columbia University, where he earned his master's degree in 1917 and his Ph.D. in 1925 under the direction of Robert S. Woodworth.

During World War I, he worked with the United States Army to develop psychological tests to screen new draftees while studying under Charles Spearman and Karl Pearson.

After short stints at various locations (including five years in private practice), Wechsler became chief psychologist at Bellevue Psychiatric Hospital in 1932, where he stayed until 1967.

This battery differed greatly from the Binet scale which, in Wechsler's day, was generally considered the supreme authority with regard to intelligence testing.

The tests are still based on his philosophy that intelligence is "the global capacity to act purposefully, to think rationally, and to deal effectively with [one's] environment" (cited in Kaplan & Saccuzzo, p. 256).