Plants regulate cellular processes based on the presence or absence of light through a combination of anticipatory (circadian) and reactive (light responsive) mechanisms. Together, these mechanisms allow plants to dynamically adapt to their daily environment as well as signal developmental events (e.g. flowering). Much of our knowledge regarding diurnal regulation of plant cell processes has been derived through transcriptomics. To date, the extent to which diurnal plant cell regulation is controlled by changes in protein abundance and/or post-translational protein modifications (PTMs) remains poorly understood. We currently employ quantitative proteomics to examine the model plant Arabidopsis thaliana from a systems perspective, with identified targets of interest further investigated using a combination of molecular and cellular biology, biochemistry as well as targeted proteomics.