The nature of the metal-silicon double bond is investigated using ab initio wavefunctions. Electron correlation is specifically included in the calculations at the FORS-MCSCF (full optimized reaction space multiconfiguration self-consistent field) level of theory. Silylene complexes of the form MSiH2 +,containing metals from the first transition series (M = Sc, Ti, V, Cr, Mn, Fe, Co, and Ni), are chosen for this study. An analysis of the bonding and electronic structure among the silylene complexes is presented. The silylene complexes are compared to representative car bene analogues, MCH2 +, and to CrGeH2 + and CrSnH2+.