Gwydion Suilebhan advocates for writers and for the art of writing, both locally and nationwide, in a variety of ways.

For the past five years, he has served as the Executive Director of the PEN/Faulkner Foundation, a non-profit organization that champions the breadth and power of fiction in America. PEN/Faulkner is widely known for giving out the PEN/Faulkner Award for Fiction, but the organization also holds public literary programs and brings authors into under-served DC schools.

Suilebhan also serves as the Project Director of the New Play Exchange, the world's largest digital library of scripts by living writers, as a consultant to the National New Play Network. The NPX, as the platform is known—which Suilebhan conceived of in a 2012 HowlRound article and began architecting shortly thereafter—has been providing a transparent, egalitarian way for producers, writers, and theater educators and students to connect with each other and discover new resources since January of 2015. It serves more than 2,000,000 subscribers.

After six years as the Regional Representative to the Dramatists Guild for Washington, DC, Suilebhan was elected to the Dramatists Guild Council in 2017, serving a three-year term. In 2023 he joined the board of the Alliance for Jewish Theatre.

As an advocate for artists in his home city, Suilebhan co-founded The Welders, a Helen Hayes Award-winning DC-based playwrights collective designed to put writers in control of their own creative destinies. In addition, he conducted a multi-year demographic analysis of the plays, playwrights, and directors that made up the DC theater ecosystem.