MapLight California combines three data sets:
- Contributions: Campaign contributions given to each member of the California State Legislature. We currently include contributions made since January 1, 2003 to legislators who have served in the 2009-2010, 2011-2012, and 2013-2014 sessions. (Source: National Institute on Money in State Politics)
- Support/opposition: Which interest groups and companies support and oppose key bills. (Source: MapLight research team, LegInfo)
The data provided on the MapLight Web site is accurate as best as can be determined.