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Knowledge of the Earth's atmospheric optical turbulence is critical forastronomical instrumentation. Not only does it enable performance verificationand optimisation of existing systems but it is required for the design offuture instruments. As a minimum this includes integrated astro-atmosphericparameters such as seeing, coherence time and isoplanatic angle, but for moresophisticated systems such as wide field adaptive optics enabledinstrumentation the vertical structure of the turbulence is also required.  Stereo-SCIDAR is a technique specifically designed to characterise theEarth's atmospheric turbulence with high altitude resolution and highsensitivity. Together with ESO, Durham University has commissioned aStereo-SCIDAR instrument at Cerro Paranal, Chile, the site of the Very LargeTelescope (VLT), and only 20~km from the site of the future Extremely LargeTelescope (ELT).  Here we provide results from the first 18 months of operation at ESO Paranalincluding instrument comparisons and atmospheric statistics. Based on a sampleof 83 nights spread over 22 months covering all seasons, we find the medianseeing to be 0.64" with 50% of the turbulence confined to an altitude below 2km and 40% below 600 m. The median coherence time and isoplanatic angle arefound as 4.18 ms and 1.75" respectively.  A substantial campaign of inter-instrument comparison was also undertaken toassure the validity of the data. The Stereo-SCIDAR profiles (optical turbulencestrength and velocity as a function of altitude) have been compared with theSurface-Layer SLODAR, MASS-DIMM and the ECMWF weather forecast model. Thecorrelation coefficients are between 0.61 (isoplanatic angle) and 0.84(seeing).

Optical turbulence profiling with Stereo-SCIDAR for VLT and ELT