The large number of elastic and inelastic collisions which take place during supersonic gaseous expansions produce not only acceleration and internal cooling of molecules, but also their alignment or orientation. The collisional alignment of the rotational angular momentum, corresponding to the orientation of the benzene molecular plane, in supersonic seeded expansions with lighter carrier gases is demonstrated via two complementary experiments: one interrogating benzene via polarized laser light IR absorption the other one probing its orientation via molecular beam scattering on rare gas targets. Typical seeding gases are helium, neon and their mixtures, and molecular hydrogen. Total stagnation pressures are of the order of similar to1 bar and similar to0.1 mm nozzle. A propensity is demonstrated for benzene molecules in seeded molecular beams to fly with the molecular plane preferentially oriented parallel to the molecular beam propagation direction. The analysis of the experimental results has been carried out using a phenomenological model which provides the fraction of molecules traveling in such a "frisbee'' mode. A frisbee propensity function is defined and found to range between 0.71 and 0.85, corresponding to IR and to scattering experiments, respectively. These values are significantly higher than the value 2/3, expected for a random distribution of molecular plane orientations. The trend in the measured values is discussed in terms of different angular cones of the supersonic expansion sampled in the two experiments and evidence is provided that the orientation is higher the narrower is the sampled cone aperture. (C) 2003 American Institute of Physics.