Conservative senator Jeanine Anez was unknown to many Bolivians before she stepped out beaming and waving a Bible on the balcony of the government palace.
A longtime critic of her leftist predecessor Evo Morales, she stepped into the power vacuum left when he suddenly fled the country to escape a violent crisis.
Now all eyes in the country are on Anez, a 52-year-old lawyer from the northeastern region of Beni, bordering Brazil.
As second deputy speaker of the Senate, Anez was sworn in by her allies after all the other officials in line to act as interim president had fled.