Internet company Google will publicly oppose an attempt to ban same-sex marriage in California.
Co-founder Sergey Brin said in a blog posting that the company, which is headquartered in the state and employs nearly 20,000 people, sees the issue as one of equality.
It is unclear if Google will contribute to the campaign opposing Proposition 8.
In the past weeks Hollywood celebritities Brad Pitt and Steven Spielberg have donated to the campaign.
Proposition 8 is an initiative measure on the 2008 California General Election ballot in November.
It would amend the state Constitution to “eliminate right of same-sex couples to marry.”
In May the California Supreme Court overturned a ban on same-sex marriages in the state.
The Court voted 4 to 3 to strike down the ban.
Opponents of gay marriage raised more than a million signatures to place the initiative on the November ballot.
“While there are many objections to this proposition – further government encroachment on personal lives, ambiguously written text – it is the chilling and discriminatory effect of the proposition on many of our employees that brings Google to publicly oppose Proposition 8,” wrote Mr Brin.
“While we respect the strongly held beliefs that people have on both sides of this argument, we see this fundamentally as an issue of equality.
“We hope that California voters will vote no on Proposition 8 – we should not eliminate anyone’s fundamental rights, whatever their sexuality, to marry the person they love.”
Human Rights Campaign, America’s largest gay, lesbian, bisexual and transgender civil rights organisation, named Google on its annual list of the “Best Places to Work for GLBT Equality” earlier this year.
A total of 195 US companies scored a perfect 100% on the Human Rights Campaign Foundation’s Corporate Equality Index which measures policies and practices implemented to promote fairness and equality in the workplace for GLBT employees.
Mr Brin founded Google with Larry Page in 1998. The search engine had revenues of $16.6 billion (£9.2bn) last year.