In this paper, different approaches of building and expanding conceptual classes are presented. Classes are built using syntactic and semantic information provided by a corpus. Then, expansion is addressed by two different methods. The first method deals with the objects of syntactic relations found in the corpus. Relations between classes are thus designed. They are called induced relations. Then we use objects of induced syntactic relations (called complementary objects) to expand conceptual classes. We propose an automatic experimental protocol to measure the relevance of the provided concepts. The protocol helps alleviating the judgment effort of a human expert. The second method expands concepts with more global terms by using Web knowledge associated with the existing concepts. Both methods are evaluated and mixed in order to provide the most reliable technique in expanding conceptual classes.