TIME is a difficult concept to grasp in Biology. However, cells seem to have no difficulty perceiving and decoding it over our life-time. This is particularly evident during embryo development, when one single cell gives rise to multiple tissues and organs according to a predictable temporal pattern of events. The formation of the embryonic precursors of the vertebral spine – the somites – is a paradigmatic example of temporal control of morphological events. Somitogenesis takes place over time, in a rostral-to-caudal manner, and is governed by a tightly regulated molecular oscillator: the Embryo Molecular Clock. We aim to understand (1) the molecular mechanisms that underlie the periodicity of the embryo clock, and (2) how gene expression oscillations convey temporal information during cell differentiation.