I think this picture must have been taken at the 1968 Dulles prom at the Warwick Hotel. That's Matthew Hall (Class of '68) and Cindy Buehring Gustin (Class of '70).
I don't know whose birthday they are celebrating, but the location is the Buehring family home on Oyster Creek Drive. The date must be 1969 or '70 because exchange student, Nilginn Serdaroglu, appears in the photo. (She is third from the right.) That's Claudia Rozelle and Cindy Buehring on the right. Bunnye Buehring is wearing the red sleeveless sweater on the left. I'm not certain who the others are.
I found this newspaper clipping very interesting. I never knew the Neals hosted Brian Bourne, the second DHS exchange student. I thought Nilginn was the second. I didn't know Gary Buis (DHS '70) was an exchange student in Spain.