A thermotropic main-chain polyether based on bis (4-hydroxyphenoxy)-p-xylylene and 1,11-dibromoundecane has been studied by variable-temperature solid-state C-13 NMR. Between isotropization and glass transition temperatures, the material can be identified to be semicrystalline, consisting of two conformationally and motionally distinguishable phases. The more mobile component is liquid-like and thus, can be attributed to an amorphous phase. In the more rigid component, the molecules have a conformationally disordered methylene sequence. In the low-temperature ordered phase approximately 2/3 of the carbon-carbon bonds are trans (t). Starting from the bond between the oxygen and the first methylene carbon, the bond conformations are : d - t - d - t - t - t - t - t - t - d - t - d, where d stands for disordered (i.e., it represents the common dynamic interchange between gauche and trans with an overall gauche content of perhaps 40%). The motion of the alpha,alpha’-diphenoxy-p-xylylene unit consists mainly of 180-degrees ring-flips, which cause no entropy increase relative to ordered phenylene groups in a crystal, but significantly changes the C-13 NMR spectra. The central p -xylylene ring starts its flipping motion at a lower temperature than the two phenoxy rings. The high-temperature mesophase contains a methylene sequence of the bond conformations : d - t - d - d - d - t - t - d - d - d - t - d. Thus, the difference between the low-temperature and high-temperature mesophases consists of different degrees of conformational disorder. Thermal analysis seems to indicate that additional mesophases may be possible.