That summer he entered field as an assistant to Harvard's Roland Dixon to study American Indian languages of California.

He began at the Hacienda Chichén, owned by U.S. Consul to Yucatán Edward H. Thompson, a large plantation that included the ancient city of Chichen Itza.

During one of his seasons at Chichen Itza he helped Thompson dredge the Cenote Sagrado; at the end of another, he carried artifacts to the Peabody Museum in his luggage.

[6] In 1903, Tozzer traveled to Campeche and Chiapas to conduct research among the Lacandon Maya, and lived for several weeks in a small settlement on Lake Pethá, witnessing and even participating in their ceremonies.

In the summer of 1907, he joined Dixon, Alfred Kidder and Sylvanus Morley on a purely archaeological expedition to Rito de los Frijoles in New Mexico (today part of Bandelier National Monument).

In 1910 he took a leave of absence from Harvard to lead his first expedition to the ruins of Tikal and Nakum on behalf of the university's Peabody Museum.

In 1914 Tozzer took another leave of absence to succeed Boas as director of the International School of American Archeology and Ethnology in Mexico.

[18] His magnum opus, "Chichen Itza and its Cenote of Sacrifice" (Cambridge, Massachusetts: Memoirs of the Peabody Museum, 1957), was published after his death in 1954.

A massive volume with hundreds of illustrations, "It covers every aspect of Chichen Itza: its history, religious cults, arts, and industries as well as contacts with other regions," noted Samuel Kirkland Lothrop in his obituary of Tozzer.