2846 20160701171711.0 ASTROimport-1003 Blomme, R. 2011 Finding Early-type Stars in the Gaia Catalogue The Gaia satellite will provide accurate parallaxes and photometry (330-1000 nm) for 1 billion stars down to magnitude 20. In addition, spectra (847- 874 nm) will be taken for 150 million stars down to magnitude 16. Among those targets, there will be a large sample of O and B type stars. According to the Besancon Universe model (Jordi Carrasco [2007], ASPCS 364, 215), about 900,000 B stars should be observed. About one sixth of these stars (Briot Robichon [2004], ESA SP-576, 561) are expected to have parallaxes with a relative precision better than 3%. This large number will enable us, for the very first time, to perform unbiased statistical analyses and high-accuracy luminosity determinations based on a homogeneous dataset. It will also allow us to study the dynamics of the open clusters in which these stars are formed. Stellar Clusters Associations: A RIA Workshop on Gaia 2011 377-378 http://esoads.eso.org/abs/2011sca..conf..377B published in NONREF