The chloroplast stromal CLP protease system is essential for growth and development, consisting of a proteolytic core complex that interacts with ClpC1, ClpC2, or ClpD AAA+ chaperones. In this study, an in vivo ClpC1 substrate trap with a C-terminal STREPII affinity tag was generated, and MS/MS analysis identified many proteins that were highly enriched compared to the ClpC1 WT control.