Plant responses to ultraviolet (UV) radiation are numerous, resulting in rapid and permanent alteration to numerous aspects of plant form, physiology and biochemistry. Such responses to UV and UV-B (290–320 nm) radiation in particular have been previously studied largely due to concerns over ozone depletion, but a recent refocus towards the effects of environmentally relevant UV-B doses has provided an opportunity to investigate the mechanistic basis for several well defined plant responses. We have characterised some of these underlying mechanisms using a combination of crop species and Arabidopsis mutants, in an effort to build up a model of whole-plant response. (1) The role of UV in regulating leaf growth has been investigated using Lactuca sativa as a model species in a top-down approach, whereby leaf expansion rate, leaf biophysical properties, cell growth and cell wall peroxidase content have been subject to UV-B mediated change. (2) Upregulation of secondary metabolite biosynthesis has also been characterised in L. sativa, with UV absorbing compounds increased according to UV-B, plus leaf anthocyanin (pigment compound) concentration elevated by 60% in plants exposed to the highest UV dose compared to control. (3) The importance of various key pathways to the UV whole plant response are also currently under investigation with a selection of A. thaliana mutants. Such findings will not only add to the understanding of fundamental photobiological responses, but are also currently being successfully integrated into sustainable agronomic practice.