A search for new particles (X) that decay to electron or muon pairs has been performed using approximately 200  pb−1 of pp collision data at s√=1.96  TeV collected by the CDF II experiment at the Fermilab Tevatron. Limits on σ(pp→X)BR(X→ℓℓ) are presented as a function of dilepton invariant mass mℓℓ>150  GeV/c2, for different spin hypotheses (0, 1, or 2). The limits are approximately 25 fb for mℓℓ>600  GeV/c2. Lower mass bounds for X from representative models beyond the standard model including heavy neutral gauge bosons are presented.