This study describes the clay mineralogy of the Lower Cretaceous （Barremian） rocks of the Wessex Basin for palaeoenvironmental interpretations. Seventy-four samples were subjected to optical microscopy， scanning electron microscopy/energy-dispersive x-ray spectroscopy （SEM/EDS）， and Quantitative Evaluation of Minerals by Scanning Electron Microscopy (QEMSCAN?) techniques. The results revealed an illite-dominated sedimentation in most sections of the basin， with kaolinite， chlorite， smectite and glauconite occurring in subordinate quantities. Inferred paleoclimatic conditions from the clay mineral trends indicates a warm and dry climate， with seasonal precipitation. Kaolinite to illite ratios indicate that more arid climate conditions were prevalent but brief periods of warm and humid conditions were also present. A strong positive correlation between chlorite and tourmaline indicates that excess chlorite may have been contributed from tourmaline-chlorite-schists in a tourmaline-dominated provenance. SEM confirms that most of the clay minerals are detrital in origin but authigenic kaolinite is also present as vermiform and mica-replacive kaolinite which formed during early diagenetic modification from flushing meteoric waters in warm humid climates. This study is significant because it demonstrates the importance of multi-proxy methods for understanding clay minerals within sedimentary basins for interpreting the palaeoclimatic conditions of depositional systems.