About Big Sister Letters

Big Sister Letters is a monthly snail-mail subscription for girls ages 9–16 that delivers thoughtful physical letters, confidence-building guidance, and support for the grown-up beside her.

In a world dominated by screens, we believe there is something deeply powerful about receiving a real letter — something she can hold, reread, and keep. Each envelope is written with care, designed for her age and stage, and paired with a companion guide to help the adults who love her most support her well.

Our mission is simple: to give every girl the kind of honest, encouraging guidance that builds confidence instead of confusion. We write about friendship, body changes, identity, boundaries, and all the in-between moments that make growing up feel both exciting and overwhelming.

Founded by Genevieve Monacelli, a New York State certified Health and Physical Education teacher with 10 years of middle school experience, Big Sister Letters grew out of a calling to extend support beyond the classroom and into the hands of girls who need it most.

We mail on real paper. We write with real care. And we believe every girl deserves to grow up informed, confident, and proud of who she is becoming.