The Oscar-winning actress, 45, has spent the last five years working with the national education nonprofit City Year to help students stay in school and graduate.
"I love working with kids and seeing the light come on when they realize they are smart," Spencer tells PEOPLE. "It's so beautiful to watch."
Spencer first got involved with City Year when she attended their annual Spring Break benefit in Los Angeles, and says after seeing the work they do she immediately wanted to help.
"Their goal is to get as many kids as possible across that line to graduation," explains Spencer. "They start in grade school, because if you get a child in their formative years to stay engaged in school you will get them to graduate."
For more on Spencer and City Year, pick up the new issue of PEOPLE, on stands Friday.
The organization, which works with nearly 300 public schools across 27 U.S. cities, helps individual students through their mentoring program.
Spencer says she felt a personal connection to the work they are doing.
"City Year resonated with me because when I grew up, we were poor – and an education is a way out of poverty. It's a way out of the current situation that can seem isolating and hopeless for some kids. When you give kids the tools necessary to change their destiny, it's really empowering," said the Alabama native.
On Saturday, Spencer will once again serve as a celebrity host at City Year's annual star-studded Spring Break event, which features musical performances, food and games.