Article Contents • Introduction • Growth in Osmotrophs (Including Autotrophs) • Growth in Non-osmotrophs • Individual Growth • Population Growth • Growth at Other Biological Levels Online posting date: 15 th July 2016 Growth is a process fundamental to life. It implies an increase in not only energy and information but also in matter content. Recent advances in ecology have demonstrated that the elemental composition of organisms-their stoichiometry-is inextricably linked to their growth rate. Unbalances between the demands of elements for growth and their relative availabilities often result in elemental limitation. Also, different cellular components have different elemental compositions, and thus changes in allocation between uptake and assembly machineries affect both growth rate and elemental composition at the organismal level. Osmotrophs (including autotrophs) acquire essential elements through a vast set of separate molecules, resulting in more flexible stoichiometries compared to non-osmotrophs that ingest their preys in one package. Relationships between elemental composition and growth rate should be considered separately for individuals and for populations, as processes and mechanisms differ between the two scales, and more generally among the various biological scales.