Membrane proteins and antimicrobial peptides represent two diverse and challenging classes of macromolecules to characterize at the molecular level. They are linked by the interaction with the lipid bilayer of the cell membrane. Within the lipid bilayer, membrane proteins are involved in vital biochemical processes such as ion transport, signal transduction and cell adhesion. Antimicrobial peptides are a broad class of polypeptides produced by all living organisms, representing the first line of defense against bacterial infections. They work by selectively targeting the bacterial membranes and subsequently killing the cell by a variety of mechanisms such as membrane disruption, membrane potential dissipation and enzyme inactivation. Although very important, membrane proteins and antimicrobial peptides are underrepresented in terms of available high-resolution structural information compared to water-soluble proteins and this limits the current understanding of how they work in living cells. In this thesis I summarize my contribution towards the elucidation of the high-resolution structures of the integral membrane protein phospholamban and the mechanism of action of two important antimicrobial peptides LL37 and distinctin) by a hybrid solution and solid-state nuclear magnetic resonance spectroscopy approach. These results provide new insights and methodologies to study and understand how key membrane proteins and antimicrobial peptides elicit their function.