An archaeological evaluation comprsising of six trenches was undertaken at Cassiobury School, Coningesby Drive, Watford between the 2nd and 4th of may 2012. The only archaeological features encountered comprised of a probable root disturbance in Trench 5 and a small rectangular pit or posthole in Trench 6. Both of these features cut the natural alluvial stony clay and were sealed by a subsoil which was observed in all of the trenches. A flint blade was recovered from the pit/posthole.Two modern service trenches cut the subsoil in Trenches 2 and 6 and were in turn sealed by topsoil. One layer of made ground was also observed in Trench 4 between the subsoil and the topsoil.