The Monte Carlo simulation of light transport in scintillator basically provides two types of important information: (a) the light transport contributions to time and energy resolutions, and also (b) the influences of surface coverings of scintillator cell or/and lightguide on the detector response. The above information can be exclusively obtained within the framework of a precise Monte Carlo light transport simulation. This book aims to provide the basic techniques and information required for modelling light transport in scintillation detectors.