Mission San Francisco Solano was the 21st, last, and northernmost mission in Alta California. It was named for Saint Francis Solanus. It was the only mission built in Alta California after Mexico gained independence from Spain. The difficulty of its beginning demonstrates the confusion resulting from that change in governance. The California Governor wanted a robust Mexican presence north of the San Francisco Bay to keep the Russians who had established Fort Ross on the Pacific coast from moving further inland. A young Franciscan friar from Mission San Francisco de Asis wanted to move to a location with a better climate and access to a larger number of potential converts.

The Spanish missions in California formed a series of 21 religious outposts or missions established between 1769 and 1833 in what is now the U.S. state of California. The missions were established by Catholic priests of the Franciscan order to evangelize indigenous peoples backed by the military force of the Spanish Empire. The missions were part of the expansion and settlement of New Spain through the formation of Alta California, expanding the empire into the most northern and western parts of Spanish North America. Civilian settlers and soldiers accompanied missionaries and formed settlements like the Pueblo de Los Ángeles.