Multi-phase wetting and coalescence are ubiquitous in nature and technology alike. In particular, a good understanding of wetting and coalescence is crucial for the successful application of inkjet printing technology and for its future development towards, e.g., additive manufacturing. Inspired by phenomena encountered in inkjet printing, this thesis presents several fundamental studies of wetting and coalescence problems. In particular, we focus on the role of liquid substrates and physico-chemical interactions between components in multi-phase systems.