Cement displacement efficiency significantly affects the quality of a well cementing job. Inefficient displacement of drilling fluids by spacers and cement slurry results in poor placement and potential contamination of the cement, which in turn can compromise cement integrity and threaten zonal isolation of oil and gas wells. In this paper, a novel method is introduced to monitor the cement displacement process in real time using fiber optic distributed temperature and strain sensing (DTSS) technologyas drilling fluid, spacer and cement are pumped through the casing annuli.An advanced DTSS system, based on hybrid Brillouin and Rayleigh backscattering, was used in combination with a specially designed fiber optic cable to identify the location of each fluid (i.e. drilling fluid, spacer fluid and cement slurry) during the cement displacement process. The fiber optic cable consists of a single-mode optical fiber packaged with a polymer that has selective sensitivity to various well construction fluids, and thus can be used to detect the presence of each fluid. Both strain and temperature changes were monitored by the DTSS system to track the cement displacement process. When the proposed fiber optic cable was exposed to synthetic-based mud (SBM) and spacer fluid, the strain values recorded by the fiber differed by a few orders of magnitude. When the cable is exposed to cement slurry, the location of cement can be determined from its exothermic heat release signature, which is apparent in both strain and temperature measurements. Contamination of cement slurry with drilling fluid was found to have a significant impact on the strain and temperature profiles. Thus, the DTSS system can provide useful information regarding top of cement (TOC), the wait-on-cement (WOC) time and the displacement efficiency in real time. Cement displacement of drilling fluids and spacer fluids has been modeled in the past; however, to date the displacement process and the locations of these fluids have never been tracked and verified in real time. This paper presents a new way for real-time, in-situ, continuous, and non-disruptive monitoring of the cement displacement process and tracking of the well construction fluids.