Colour octet effects in quarkonium physics

The importance of including colons octet contributions in describing decay and production. of quarkonium states is briefly discussed for two cases : t he radiative decays of the Y and the production of J/psi in the inclusive B decays. It is shown how information on the non-perturbative matrix element s can be obtained by comparing the theoretical expressions computed at next -to-leading order in alpha(s) with the experimental data.