Before the colonization of the region by Spain, Lafayette and its vicinity were inhabited by the Saclan tribe of the indigenous Bay Miwok. Ohlone also populated some of the areas along Lafayette Creek. The indigenous inhabitants' first contact with Europeans was in the late 18th century with the founding of Catholic missions in the region. These initial contacts developed into conflict, with years of armed struggle, including a battle on what is currently Lafayette soil in 1797 between the Saclan and the Spanish, and eventually resulting in the subjugation of the native population.
Most of what is currently Lafayette was given as a Mexican land grant, Rancho Acalanes to Candelario Valencia in 1834. The name Acalanes seems to have come from the name of a native village in the area, Ahala-n.
American settlement started with the arrival of Elam Brown from St. Joseph, Missouri, in 1846. He purchased Rancho Acalanes in 1848. The settlement continued to steadily grow due to its proximity to San Francisco; starting with Brown's group of 18 settlers, by the census in 1852, 76 people were listed as living in the area. Brown founded a mill in 1853. A school began in 1852 in a one-room schoolhouse, taught by a 25-year-old Kentucky migrant, Benjamin Shreve. By 1865 the school had expanded to 43 students in five classes, and so in 1868 a tax levy of $1,000 was used to build a new schoolhouse; school expanded from a five-month year to a nine-month year. In 1893, a new schoolhouse was built to accommodate the increasing number of students; this building still stands today.
On March 2, 1857, the LaFayette post office was established by the U.S. Postal Service. (The official document giving this exact date was supplied to the Lafayette Historical Society in 1993 by the Historical Division of the U.S. Postal Service.) Prior to 1857 the community that is now known as "Lafayette" actually had no known name - though there are undocumented rumors that it was called Dog Town, Brown's Corner, Brown's Mill, Acalanus, and perhaps Centerville.
The name "LaFayette" came together with the community's first post office. In 1857 Benjamin Shreve, owner and manager of a roadside hotel-general store (which faced today's Lafayette Plaza), applied for a post office for the community, first requesting the name Centerville. When informed that a post office with that name already existed in California, Shreve suggested La Fayette, after the French general who became a hero of the American Revolution (probably not because his wife was a native of Lafayette, Indiana). The first LaFayette post office was established at 3535 Plaza Way and Shreve became the town's first permanent postmaster, holding the job for 30 years.
Spelling: On the original document from the U.S. Postal Service, dated March 2, 1857, the name “LaFayette” is unmistakably written as one word with a capital “F” in the middle. In 1864 the place name "Lafayette" first appeared on a map of the area, titled "Bancroft's Map of California, Nevada, Utah and Arizona (copyrighted 1863. Scale: 24 miles to 1 inch). Yet research by Ruth Dyer, Lafayette historian, shows that the name of the post office and of the new town itself soon began to be written as two words, “La Fayette.” By 1890 it had changed to one word, "Lafayette," and so appeared in an official communication from the U.S. "Post Office Department" in Feb. 1899. Then by 1905 it was back to two words. Finally on March 31, 1932 the name of the post office was officially changed to Lafayette, which has remained unchanged to this day. Lafayette was the tenth post office established in Contra Costa County. (See Salley, History of California Post Offices).