The polarizabilities of the (J=1, M=0) and the (J=2, M=0) rotational states of the gaseous NaLi molecule have been measured by observing the refocusing voltages of a supersonic molecular beam with an electric quadrupole state selector. From these measurements the molecular electric dipole moment μ = 0.47 ± 0.03 D and the molecular electric polarizability were determined. The dipole moment is a factor of 2 smaller than predicted by two recent extended Hartree—Fock calculations (optimized valence configuration and configuration interaction), indicating a need for a more exact description of the bonding. The molecular polarizability is approximately equal to the sum of the atomic polarizabilities.