California Proposition 1 may refer to:
1998 California Proposition 1, concerning property tax valuation 1998 California Proposition 1A, concerning bonds related to education 2004 California Proposition 1A, concerning revenue collected by local government 2006 California Propositions 1A–E, concerning taxes and bonds for several programs 2008 California Proposition 1A, concerning high-speed rail 2009 California Propositions 1A–F, concerning several reforms to state law 2014 California Proposition 1, concerning bonds to upgrade California's water system 2018 California Proposition 1, concerning veterans' home loans and affordable housing 2022 California Proposition 1, concerning abortion and contraception 2024 California Proposition 1, concerning mental health treatment