The gathering will take place at 10 a.m. on the steps of the Lake County Courthouse, 255 N. Forbes St., Lakeport.
On Tuesday the California Supreme Court will issue its opinion on the validity of Proposition 8, the voter-approved ban on same-sex marriage, passed last November.
Also to be decided is the future of the 18,000 gay couples who were married prior to the proposition's passage by 52 percent last November.