In quantitative portfolio management, combining optimization with estimation causes concern for asset managers because portfolio problems may be sensitive to deviations in their inputs, but obtaining accurate input estimates is a difficult task. Robust factor models address these concerns using factor models for estimating asset returns and worst-case approaches for gaining stability in portfolio performance. Recent studies on robust factor investing explore methods of incorporating factors into robust portfolio construction. In this article, the authors provide a survey that includes theoretical insight, empirical findings from historical data, and experience from practitioners in formulating and executing robust factor-based investment strategies.