The interaction of C60 with single-wall carbon nanotubes (SWNTs) and graphite is studied experimentally by thermal desorption spectroscopy (TDS) and theoretically by molecular-mechanics and -dynamics calculations. The van der Waals parameters and force field for C60-graphene and C60-SWNT interactions are derived from the low-coverage C60 binding energy to the graphite surface. We use these to compare the efficiency of different mechanisms by which C60 can be encapsulated into SWNTs.