Multicellular development is a sequence of genetically programmed, intricately linked micro- and macroscopic events that start from a single cell - zygote - and lead to the formation of a functional individual, primed for survival and reproduction. All developmental events, fromgene expression to cell division, differentiation andmigration, as well as tissue and organ formation, have to follow a precise temporal and spatial order, as the smallest mistake can be detrimental. Development is remarkably reproducible, despite occurring under a wide variety of environmental conditions, such as nutrient availability and temperature, and being subject to a substantial amount of molecular noise. In this thesis, we use the nematode worm Caenorabditis elegans as a model system to investigate i) how the timing of development adjusts to changes in the outside world and ii) how organisms respond to external stresses that do not support normal developmental progression. C. elegans is an ideal model organism to address these questions, due to its simplicity, stereotypical developmental pattern and the vast extent to which its biology and genetics are known. @en