Seeing is believing. To illustrate the importance of chemical biological approaches to the biomedical community, the identification of fluorescent small molecule probes with new attractive properties in terms of cellular/subcellular specificity and colour should prove invaluable. Our strategy relies on the identification of cellular fluorescent probes by screening our 90,000 compound diversity library and use identified fluorescent scaffolds to improve their properties by synthetic chemistry, with the ambition to complement existing dyes. 225 hit compounds with specific intracellular staining pattern cluster around nine chemical scaffolds. Using these scaffolds as basis, we will attach fluorescence-modifying moieties to explore an enlarged chemical space and improve our chances to engage biological entities specifically. We plan to generate modified emission wavelengths and quantum yields though push-pull effects, enlargement of conjugate systems and supramolecular entities. Resulting compounds will be profiled for their staining specificity in cell lines and primary blood cells. Compounds with the most attractive specificity and fluorescence properties will be characterized for their cellular uptake route, metabolism, activity and, importantly, their molecular targets. The cellular colour chart project (3C) aims to generate a minimum of one, hopefully more, new fluorescent molecules that probe cellular processes with a molecular understanding of their biological specificity.