Irish folk dance classes in Montgomery County, Maryland are taught by the Ring of Kerry Irish Dancers. A great recreational activity, Irish dancing provides aerobic exercise in a welcoming social setting. For prospective new members, the first class is free!
Transceltic lists Celtic festivals in the USA and worldwide. Bill Lynch's Sets.ie site shows major set dance events around the globe.
How about participating in a hurling match? DC Gaels is an amateur club that promotes Irish sports in the DC Metro area. The Gaels have both ladies' and men's Gaelic football teams as well as hurling and camogie teams. They also have a youth league.
For general information about folk dancing and music of all kinds in our area, there's the Folklore Society of Greater Washington. Focus Music lists Washington, DC - Baltimore area folk and acoustic music resources. And the inestimable Mary Cliff has her (Word document) lists of all things folk for the DC metro area. Plus she has a show featuring traditional music every Saturday night from 9 to midnight on WERA. Some other Celtic music and arts resources are: