  Electroweak Sudakov logarithms at high energy, of the form
alpha/(sin^2theta_W)^n log^m s/M_{Z,W}^2, are summed using effective theory
methods. The corrections are computed to processes involving two external
particles in the standard model. The results include non-zero particle masses,
such as the t-quark mass, electroweak mixing effects which lead to unequal W
and Z masses, and radiative Higgs corrections proportional to the Yukawa
couplings. We show that the matching at the scale M_{W,Z} has a term at most
linear in log s/mu^2 to all orders. The effective theory formalism is compared
with, and extends, previous work based on infrared evolution equations.
