This paper focuses on intervention effects obtained by embedding a topic constituent (either a displaced topic or a clitic left-dislocated topic) within the domain of wh-movement. We present the results of two acceptability judgment tests carried out in European Portuguese (EP), which indicate that only a subset of the constructions in which a topic intervenes in the path of wh-movement is judged acceptable by native speakers. The pattern that emerges can be described by the following generalization: (1) A wh-movement dependency may contain a topicalized or clitic left-dislocated constituent in its scope iff the full topic-(cl)-gap dependency is contained within the path of wh-movement . This generalization indicates that a version of the no crossing constraint (e.g., Fodor 1978; Pesetsky 1982) holds in these configurations. We discuss the challenges faced by a purely syntactic account of (1) and suggest that a more promising line of an approach is one that attempts to derive (1) from processing constraints.