Measured equivalent widths of the interstellar x 4430 band made on spectrograms taken at the Mc- Donald Observatory are given in Table 1. The profile is found symmetric and smooth. Correlations of x 4430 with other interstellar features are given in Table 2. The band is most strongly correlated with the interstellar x 6284, fairly well correlated with interstellar reddening, and may be well correlated with interstellar polarization. Diffuse absorption bands occur in the solid and liquid states in molecules which have incomplete inner shells of electrons. Such substances are often paramagnetic, as in the case of iron alums and salts of the rare earths. It is possible that the compounds responsible for the diffuse interstellar bands also are active in the orientation of small, elongated paramagnetic grains and thus produce the interstellar polarization.