The properties of several directly polarized radioluminescent light (RL) sources are described. The RL sources are composed of a β-particle-emitting ⁹⁰Sr radioisotope coupled to polarization-oriented light-emitting plastic scintillators. The polarization of the scintillator molecules was achieved through a mechanical stress applied to the polymer matrix. The emission stability of the RL sources is described. It was found that the degree of polarization of light emitted by the sources varied from zero to 26%, depending on the matrix and scintillating material. The RL source with the highest degree of polarization was constructed from polystyrene and anthracene.