Nuclear quantum effects such as zero-point energy conservation, tunnelling, non-adiabaticity and coherence play an important role in many complex chemical systems of technological and biological importance. Zero-point energy differences are key to understanding the experimentally-observed differences in the thermodynamic properties of normal and heavy water, while both theoretical and experimental work has highlighted the role of quantum tunnelling in enzyme-catalysed hydrogen transfer reactions. Photochemical reactions, involving multiple potential energy surfaces, are implicitly quantum-mechanical in nature, while recent spectroscopic investigations are providing new insight into the role of quantum coherence in the efficient energy transfer processes observed in photosynthetic centres. This volume brings together computational and experimental researchers who are interested in developing and applying methods to use in understanding the role of quantum effects in complex systems. The topics covered in this volume include: Quantum coherence in complex environments Spectroscopic signatures of quantum effects Zero-point energy and tunnelling Emerging opportunities and future directions