Book excerpt: This book focuses on 3d transition metal centered phthalocyanine molecules and their deposition on different substrates. Phthalocyanines are an ideal prototype since they can be grown flat on many surfaces. It highlights the molecule-substrate interaction and its influence on the magnetic and spectroscopic properties of the molecules as well as the influence of ligands — reviewing both experiential and theoretical data. Since experimental setups differ and approximations in theory vary and can influence the result, a substantial part is dedicated to a thorough discussion of the different experimental and computational methods from the point of view of reliability and predictive power.