This integrative review article aims to render a systematic account of the role that teachers’ personal characteristics, such as their motivation and personality, play for teacher effectiveness. Guided by a multi-dimensional conceptualization of teacher effectiveness as comprising not only teaching performance, but also e.g., well-being, retention, and teachers’ positive relations with multiple stakeholders, we first summarize and evaluate the available evidence on relations between personal characteristics and teacher effectiveness derived in existing research syntheses (meta-analyses, systematic reviews). We then discuss implications of the findings regarding the eight identified personal characteristics—self-efficacy, causal attributions, expectations, personality, enthusiasm, emotional intelligence, emotional labor, and mindfulness—for research and educational practice. In terms of practical recommendations, we focus on teacher selection and the design of future professional development activities as areas that particularly profit from a profound understanding of the relative importance of different personal teacher characteristics in facilitating adaptive student and teacher outcomes.