This paper investigates the semantic and pragmatic conditions on specific indefinites using experimental methodology. The results of a context-based interpretation task on the scope-taking behavior of English indefinites provide empirical support for the proposal of Schwarz (2001) that the long-distance readings of a certain-indefinites and a-indefinites are derived through different semantic mechanisms. The study findings also raise new questions concerning the pragmatic conditions on the interpretation of English indefinites. An additional task probes the identifiability requirement on a certain-indefinites (Farkas 2002).