Technical Abstract: The ability of metal hyperaccumulator plant species to accumulate high concentrations of toxic heavy metals requires the coordinated uptake, transport and sequestration of these metals to avoid damage to photosynthetic mechanisms. A number of previous studies have examined how hyperaccumulating plant species tolerate and accumulate metals using whole plant, organ and protoplast specific studies. In this study the construction of stable suspension cell lines from Thlaspi caerulescens, the subsequent physiological and molecular characterization, and stable Agrobacterium mediated transformation of T. caerulescens suspension cell lines is reported. Through both short and long term physiological and molecular experiments, the behavior of these undifferentiated cell lines were examined. It was found that the T. caerulescens suspension cell lines exhibit enhanced zinc and cadmium tolerance relative to Arabidopsis thaliana suspension cell lines, which is consistent with the increased metal tolerance seen in intact T. caerulescens plants. Interestingly, the T. caerulescens cells accumulated lesser amounts of Zn and Cd than did Arabidopsis thaliana cells. Like intact T. caerulescens plants that exhibit hyperexpression of a number of transporter genes, T. caerulescens cell lines also show increased expression of HMA4, ZNT1 and MTP1 relative to A. thaliana suspension cells. Finally, the stable transformation of T. caerulescens suspension cell lines suggest a potential mechanism for further dissecting the altered metal accumulation and homeostasis seen in this metal hyperaccumulator model plant species.