We can also present a new dataset containing time-series-cross-section information on new party parliamentary entrance. The data include information from 18 West European countries during the period 1960-2010 and was gathered as a part of the PhD-project Making the Breakthrough. An Agency-Centred Perspective on New Party Entrance into National Parliament (Bolin 2012). In the PhD thesis also four in-depth case studies of new entrants in the Swedish national parliament was conducted. The thesis can be downloaded (in Swedish) from http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-54453