In a few words:
A movement of people and communities to foster a culture that embraces relationship choice.
In a paragraph:
Modern Poly exists to create and maintain a safe and supportive space where those engaged in the practice of polyamory can come together to share ideas, experiences, resources and activism regardless of race, religion, gender, sexual orientation, age or physical location. Our vision is to facilitate the creation of an active and vibrant polyamory community which spans the spectrum of personal philosophies and physically diverse locations. Our goal is to promote the creation and growth of localized polyamory organizations that will support a broader social movement by fostering communication and providing leadership education.