The actress has been hailed a heroine for stepping in after the female passenger collapsed on the train.
Moloney made the woman comfortable and stayed with her until paramedics arrived on the scene.
She tells the New York Daily News, "A young woman passed out in train and then stumbled off the train and collapsed on a platform. I had just taken an emergency first aid class, so I kind of summoned up my list of Things To Do and Not Do! She passed out, probably due to the heat.
"She was breathing fine. I just sat with her until she came to and talked to her until help arrived. People kept wanting to pour water on her face and I told them that would just make her wet. I felt like I was the person there who was responsible for her somehow. I was really happy I could help."