As more institutions of higher education engage in the practice of leadership education, the effective assessment of these efforts lags behind due to a variety of factors. Without an intentional assessment plan, leadership educators are liable to make one or more of several common errors in assessing their programs and activities. This article reviews some of the most common errors in assessing leadership programs, including failing to consider what the authors describe as the Honeymoon, Horizon, Hollywood, Halo, and Hallmark effects (otherwise known as recency, response-shift, socially desirable, and respondent biases). Suggestions for minimizing these potential issues in assessment are also included along with suggestions for practitioners and areas for future related research.