A Study of Exclusive Charmless Semileptonic B Decay and |V_ub|

We study semileptonic B decay to the exclusive charmless states pi, rho/omega, eta and eta' using the 16 fb-1 CLEO Upsilon(4S) data sample. We find B(B^0 -> pi^-l^+nu) = (1.37 +- 0.15_stat +- 0.11_sys) x 10^-4 and B(B^0 -> rho^- l^+ nu) = (2.93 +- 0.37_stat +- 0.37_sys) x 10^-4, and find evidence for B^+ -> eta' l^+ nu, with B(B^+ -> eta' l^+ nu) = (2.66 +- 0.80_stat +- 0.56_sys ) x 10^-4. From our B -> pi l nu rate for q^2 > 16 GeV^2 and lattice QCD we find |V_{ub}| = (3.6 +- 0.4_stat +- 0.2_syst +0.6-0.4_thy) x 10^-3.