Cell plasticity describes the ability of cells to readily respond to external cues and adopt new identities and functions in the absence of genetic changes. We currently lack a comprehensive understanding of the dynamics of plasticity, especially at an individual cell level. Human breast cancer cell lines are heterogeneous and known to contain a subpopulation of highly plastic cells that are more aggressive and resistant to therapies. These cells are readily identified using cell surface markers (CD24-/CD44+) enabling temporal monitoring of their dynamics and stability. We performed transcriptional profiling of these plastic cells in a series breast cancer cell lines that stably display low (MCF7 and SUM149) or high (SUM159) proportions of these cells (1.5%, 6.0% and 97.0% respectively). Upon purification and replating of the distinct plastic and non-plastic states for each cell line, the baseline proportions were re-established with in 2 weeks, indicating cancer cells are dynamic and can transition in and out of the plastic state. Surprisingly, when individual cells were sorted and allowed to expand as single-cell clones in culture, we observed wide-spread variability in their dynamics of plasticity. Some cells re-set the original parental dynamics, while others retained a wide range of bias towards either the plastic or non-plastic state. These biases were stable across over 100 days in culture. We will present ongoing work investigating the cell-intrinsic and cell-extrinsic factors involved in maintaining these individual clone dynamics. Our work has important consequences, not only in our understanding of cell plasticity, but also in the reproducibility and interpretation of any experiment involving single-cell derived clones such as CRISPR-knockout cell line generation.