In a public letter to their new daughter, Facebook co-founder Mark Zuckerberg and his wife Dr. Priscilla Chan have pledged to donate 99% of their shares in the social media platform — currently about $45 billion —  to philanthropic efforts over the course of their lives.

Zuckerberg and Chan had their first child, Max, early last week. In the letter posted to Facebook on Tuesday, the couple cited a desire to change the world for the upcoming generation.

“We will give 99% of our Facebook shares — currently about $45 billion — during our lives to advance this mission,” they wrote. “We know this is a small contribution compared to all the resources and talents of those already working on these issues. But we want to do what we can, working alongside many others.”

They also announced the launch of the Chan Zuckerberg Initiative. The organization will, at launch, be focused on “personalized learning, curing disease, connecting people and building strong communities,” Chan and Zuckerberg wrote.

Zuckerberg clarified that he will continue to serve as Facebook’s CEO for years to come, but wrote that “these issues are too important to wait until you or we are older to begin this work. By starting at a young age, we hope to see compounding benefits throughout our lives.”

Read the full letter here.