  We describe our method to find the primordial binary population in the Sco
OB2 association. We present the results of our ADONIS and VLT/NACO
near-infrared adaptive optics binarity surveys of A and late-B stars in Sco
OB2. We combine these results with literature data on visual, spectroscopic,
and astrometric binary stars. With our observations we remove part of the
selection effects present in the combined dataset. Using simulated observations
the remaining biases can be removed in order to derive the true binary
population. Detailed N-body simulations, including stellar and binary evolution
are required to derive constraints on the binary population which was present
just after the natal gas has been removed from Sco OB2, i.e., the primordial
binary population.
