Laser desorption mass spectrometry was carried out for several fullerene derivatives (C60O and a series of 6-6 ring-bridge closed adducts of C-60 With bis(ethoxycarbonyl)methylenes C-61(COOEt)(2), C-62(COOEt)(4), and C-63(COOEt)(6)) to investigate laser-induced; growth reactions between the desorbed species. A clear correspondance between the size distribution of fragments of the parent species and the desorption-induced reaction products indicates an efficient mechanism by which reactive fragments, produced by the desorption laser, aggregate or coalesce. The reaction mechanism and nature of the products were probed through fluence dependence studies and the detection of delayed electron emission.