One of the miracles of the cell is how vast numbers of macromolecules, including proteins, lipids, carbohydrates and nucleic acids, can be maintained in highly crowded spaces with precise control over their location and activity.  This crowded cellular environment exerts immense physicochemical tendencies for protein aggregation.  Therefore, extensive quality control networks, including chaperones and proteasomal degradation machinery, operate to govern the life of each protein from synthesis and folding to transport and eventual degradation.  Our knowledge of the gene networks for protein quality control is increasingly becoming complete.  However, we still lack a quantitative measure of the capacity of the protein quality control network and how this capacity varies across different cells, upon aging or during disease or stress.  To address this we are building new biosensors to quantitate the capacity of the protein quality control systems, measure protein folding landscapes in a cell and probe mechanisms of quality control surveillance. We describe our work in progress on this goal, including toolsets that enable the folding and stability of well-studied model proteins, such as barnase and T4 lysozyme, to be characterized in vivo through genetically encoded fluorescent read-outs. Our results to date indicate success in a FRET readout of barnase foldedness, and a capacity to view the impact of protein aggregation on the effectiveness of protein quality control using an IRES fluorescent readout compatible with flow cytometry.