 The purpose of this study is to test a drug called d-cycloserine to see if it can help people with a condition called social phobia. Social phobia is also called social anxiety disorder. Social phobia is a constant fear of social or performance situations. Social situations include group gatherings of any kind. Performance situations might include times when a person would have to do something in public, such as speak up in class or at a meeting. A person with this condition worries about being embarrassed, or about other peoples opinions. People with social phobia usually feel extremely anxious nervous and worried about being the focus of attention. They often avoid social and performance situations. This behavior can have a negative effect on the quality of their lives and relationships. 