This paper uses the oblique-polarized-ray method to investigate birefringence in thin films of disklike heptameric polycyclosiloxane (HPCS). The surface birefringence B is determined at various temperatures. It is determined that B is independent of T in the region from room temperature to 40 °C, while B decreases to zero in absolute magnitude when the samples are heated further. A theoretical estimate is made of the polarizability anisotropy of HPCS molecules as Δ γ= - 450×10 ^-25 cm ³ . The orientational-ordering parameter of the HPCS molecules relative to the interphase boundaries is determined as <S>= -0.25. It is shown that the sixth-order symmetry axes of the HPCS molecules are oriented predominantly perpendicularly relative to the normal to the surface of the layer. A model is proposed for supermolecular structures, associated with the formation of domains in the form of stacks of predominantly parallel disklike HPCS molecules.