The beta and gamma radiations of the 18-hour Re188 have been examined with scintillation and magnetic spectrometers. Of the total beta disintegrations, 79% lead to the ground state, 20% to the first excited state at 155 kev, and 1% to the other excited states of Os188. The beta-ray spectra leading to the ground state and the first two excited states of Os188 are first forbidden. Thirteen gamma rays have been detected. Extensive gamma-gamma coincidence studies were made. The K-shell conversion coefficient of the 155-kev gamma ray has been obtained which agrees quite well with the E2 assignment for that gamma ray. The KL ratio also supports this assignment. No conversion electrons corresponding to the 478-kev gamma ray were found and it is concluded that it is primarily E2 in nature with a small admixture of M1 transition. A decay scheme is proposed on the basis of these data.