  The prospects to test the hypothesis of intrinsic charm quarks in the proton
are investigated. We consider how this component can be directly or indirectly
probed in deep inelastic scattering at HERA and in fixed target experiments and
find that an overlooked signal might be present in existing NMC data. Applying
the intrinsic charm model to hadron collisions we compare the resulting charm
production cross-sections with those based on standard perturbative QCD and
available data. Extrapolating to higher energies we obtain predictions for
charm production at the Tevatron and LHC.
