We study the extent to which spin assignments of new particles produced at the LHC can be deduced in the decay of a scalar or fermion C into a new stable (or quasi-stable) particle A through the chain C ! B±q,B± ! AW±,W± ! ℓ±νℓ where ℓ = e, μ. All possible spin assignments of the particles A and B are considered. Explicit invariant mass distributions of the quark and lepton are given for each set of spins, valid for all masses. We also construct the asymmetry between the chains with a W− and those with a W+. The Kullback-Leibler distance between the distributions is then calculated to give a quantitative measure of our ability to distinguish the different spin assignments.