The major discriminating factor that delineates paper chromatography from thin layer chromatography is a thin layer (0.25 mm) layer of some inert material, such as Al2O3, MgO, and SiO2, is used as substrate. Thin layer chromatography is a solid-liquid form of chromatography, whereby manipulating mobile phase organic compounds can be separated. The main advantage of thin layer chromatography over paper chromatography is its early recovery of separated components, easy visualization, and its high sensitivity. Thin layer chromatography and HPTLC (high-performance thin-layer chromatography) complement the other primary methods used for pesticide residues determinations, such as gas chromatography and liquid chromatography. An array of pesticide residues has been detected in early stage of chromatography when mass spectrometry and high-resolution mass spectrometry techniques were at infancy and at rudimentary level. Solid-phase extraction (SPE) and matrix-assisted solid-phase dispersion (MSPD) are modern sample preparation methods that are being increasingly used like C-18 cartridges. A complete description of thin layer chromatography for pesticide sample preparation have been provided in tabulated format in this chapter for readymade reckoner.