Way to go, Liv! Good Samaritan Liv Tyler stopped her car and threatened to call the police on a woman she spotted shouting at a crying baby on L.A.’s busy Santa Monica Boulevard early Thursday.

The Lord Of The Rings star is an outspoken supporter of the United Nations Children’s Fund.

“You can’t do that! I’m going to call the police. I’m going to call Child Services!” she shouted at the woman, according to X17Online.com.

The woman countered that the incident was none of Liv’s business.

The 31-year-old star, who has a four-year-old son of her own, comforted the unconsolable baby girl — who was confined to her stroller — before leaving the scene.

“When I saw that, I couldn’t take it. I had to do something,” Liv told photogs as she returned to her car.