Answer:
The Spanish missions had a profound impact (positive & negative) on the Native Californians.
Step-by-step explanation:
The California missions were set up in the 18th century with the same goal they already had achieved in Mexico: to convert Native Americans to Catholicism and expand European (Spanish) territory.
On the positive side there is the Spanish influence in culture, art, language and architecture, as we can see for example in the beautiful trainstation in San Diego.
On the negative side there is the Native American Culture (in the broadest sense) that was destroyed and being replaced by the Iberian culture that, according to some critics, brought along with it slavery, prostitution and diseases.