The attachment of specific chemical groups to individual RNAs introduces novel chemical properties and strongly influences their functionality. Individual ribosomes, mRNAs and tRNAs are dynamically modified depending on cell type and compartment, metabolic state and environmental conditions. This complexity creates specialised translational units and expands the regulatory potential of the core translation machinery. The EU-funded tRNAslation project aims to characterise key RNA modification complexes and understand the role of individual rRNA and tRNA modifications during translation elongation by creating sets of fully modified RNAs in vitro. Ultimately, this might provide mechanistic insight into links between mutations found in patients, the underlying pathways and the onset of severe illnesses.