The following year in 1893 he was the principal of Hagerstown High School, and then he resigned his post and enrolled in Indiana University.

[citation needed] Wissler received a BA in Experimental Psychology from Indiana University in 1897 and a MA in 1899.

Wissler's dissertation eventually led the psychology movement to lose interest in psychophysical testing of intelligence.

In 1924 Wissler began teaching at Yale University as a psychological researcher until 1931 when he switched to an anthropology professor, which he held until 1941.

[6] Clark Wissler performed his field research from 1902 until 1905 on the Dakota, Gros Ventre, and the Blackfoot.

While Curator, Wissler funded ethnological and archaeological fieldwork of the Northern Plains and the Southwest.

"[citation needed] Wissler states that the principal barriers that preserve the distinctness of a culture area as physical: surface, climate fauna, and flora.

Wissler also helped introduce statistics with the Pearson correlation coefficient formula which could be used to compare different artifacts in relations to their geological location.

He contributed to the culture area and age-area ideology of the diffusionist viewpoint that is no longer popular in anthropology.

[citation needed] Clark Wissler's main area of research was on Native American cultures.

[citation needed] Wissler offered some new theories that were quite different from Boas, who was a leading cultural researcher.