Two compact global mechanisms for ethylene (C2H4) diffusion flame combustion have been tailored to include important reaction steps for acetylene and benzene production. One mechanism (G11) contains 11 species with 10 reaction steps including acetylene (C2H2), and the other mechanism (G12) contains 12 species with a total of 11 reactions steps to include also the formation of benzene (C6H6). The reaction steps have been carefully selected to minimize the mechanism size for the use in large-scale computational fluid dynamics (CFD) simulations. Hence, the reaction constants have been optimized for the correct prediction of important radical concentrations. Particular focus has been on the mechanisms ability to reproduce important preferential diffusion effects and on the formation of H and C2H2 due to its importance to soot formation. The two global chemical models have been validated for a transient 1-dimensional diffusion flame configuration and show very good agreement with various detailed chemical schemes. The mechanisms are found to be nonstiff reducing typical computing time for a transient flamelet calculation (F. Mauss, 1998) from a few hours (171 species mechanism) to only a few minutes (G11).