An independent, non-partisan, media-sponsored public opinion news service. Each year the poll covers a wide range of political and social topics examining California public opinion. Poll reports 1993-2016 archived at Internet Archive. Raw data files are available from UC Data.
PPIC Statewide Surveys (Public Policy Institute of California)
Launched in 1998 with the purpose of "providing independent, objective information on the social, economic, and political forces affecting California elections and public policy preferences."
Roper Center for Public Opinion Research
Contains domestic and international survey data. The Center's Public Opinion Location Library (iPOLL) gives online access to a database including poll questions asked in US from 1936 to present.