Those who implement character education initiatives intend for those initiatives to be effective in promoting the development of character. To maximize this likelihood, it is important to consider common problems of implementation and assessment. This article addresses four challenges to effective implementation: (a) what counts as evidence of effectiveness, (b) how to know about such evidence, (c) how to implement with fidelity, and (d) how to align implementation with targeted outcomes. Assessment is critical to addressing the challenge of effective practice. Here, we examine three core areas of assessment in character education: (a) implementation (process evaluation), (b) school climate, and (c) character development (outcome assessment).