Luna Composition Lab’s mission is to close the gender gap in the field of music composition. Founded in 2016 by composers Missy Mazzoli and Ellen Reid, Luna Composition Lab provides mentorship and resources for young female, nonbinary, and gender-nonconforming composers. Luna Composition Lab is the only initiative of its kind in the United States. It has achieved national recognition as a program that not only celebrates underrepresented voices but also shapes music’s future by providing a support system for continued success. Luna Composition Lab’s signature program—the Luna Lab Fellowship—offers six young composers one-on-one mentorship with acclaimed professional composers annually. Mentors guide fellows in the composition of a new piece of music that is premiered by a professional ensemble as part of a weeklong festival in New York City. This festival includes professional development activities, masterclasses with inspirational figures, networking events, and more. In addition, Luna Composition Lab offers a series of group composition courses—Adventures in Sound—that support young female, nonbinary, and gender-nonconforming musicians who are interested in creating their own music. From notation and music theory to applied and hands-on compositional practices, students come away with a renewed sense of the possibilities for what composition can be.