Several recombinant antibody libraries associated with different screening technologies have been generated since the first steps of antibody engineering 15 years ago, in order to isolate human monoclonal antibodies. In this race to isolate antibody with virtually any specificity, innovative strategies have been developed to clone natural antibody repertoires or to increase library diversity beyond the scope of the immune system. After the in vitro transfer of the natural diversity, the second generation of partly or completely man-designed libraries was based on the available structural data of the antibody binding. Efficient selection strategies have proven critical in exploiting the potential of a library's diversity. The development and improvement of screening methods such as phage display, yeast display, ribosome display and robotic platforms have provided innovative tools to efficiently screen and sort out the desired binding specificities of billions of antibodies. Efforts to improve diversity exploration have been mainly focused on screening conditions of display techniques and the new emerging techniques. Here we review some of these prominent approaches in the field of human recombinant antibody libraries.