  We present new measurements of KL semileptonic form factors using data
collected in 1997 by the KTeV (E832) experiment at Fermilab. The measurements
are based 1.9 million KL->pi e nu and 1.5 million KL->pi mu nu decays. For
f+(t), we measure both a linear and quadratic term lambda+' = (20.64 +-
1.75)E-3 and lambda+'' = (3.20 +- 0.69)E-3. For f0(t), we find lambda0 = (13.72
+- 1.31)E-3. These form factors are consistent with K+- form factors,
suggesting that isospin symmetry breaking effects are small. We use our
measured values of the form factors to evaluate the decay phase space
integrals, IK(e) = 0.15350 +- 0.00105 and IK(mu) =0.10165 +- 0.00080, where
errors include uncertainties arising from the form factor parametrizations.
