Recent developments in the chemistry of imido and amido derivatives of selenium and tellurium in the +4, +2 and lower oxidation states are discussed. The focus is on providing an understanding of the unusual features of the structures, bonding and reactivities of these labile chalcogen-nitrogen compounds. Trends in properties within the chalcogen group are made by including comparisons with analogous sulfur-nitrogen compounds, where appropriate. For compounds in which the chalcogen is in the +4 oxidation state, the increasing reluctance to engage in pπ-pπ bonding for the heavier chalcogens is readily evident. The impressive variety of cyclic selenium imides in which selenium is in the +2 or lower oxidation states is in stark contrast to the paucity of information available concerning their tellurium analogues. Salient aspects of the ligand behaviour of selenium and tellurium imides are also described. Metal complexes of selenium(IV) and tellurium(IV) diimides are exclusively N,N′-coordinated, whereas cyclic selenium imides behave as chelating Se,Se′-donor ligands.