They marched along the banks of the River Seine, thousands of demonstrators angry about a new law allowing gay marriage and the adoption of children by same-sex couples.
SOUNDBITE: Protester Amelie, saying (French):
"We are here to defend marriage because we believe a child needs a father and a mother to grow up and that this is important so that they can grow up normally."
The controversial law adopted by parliament last month and spearheaded by President Francois Hollande enraged social conservatives who see it as anti-family.
Waving flags and chanting, "We want work not gay marriage," three streams of protesters, starting in parts of the city, were to converge on central Paris.
The law's passage makes France the 14th country to allow gay marriage.
