Background. Teachers' Soft Skills (SS) appears as a promising but problematic research area, being conceptual and methodological dispersion one of the main difficulties. Objectives. A Scoping Review was conducted, aiming to identify quantitative literature focused on teachers' SS, and synthesize the definitions, examples, methods and instruments used to approach them, as well as their main results. Methods. Online databases and reference searching were used to identify publications. Three coders select the studies based on prefixed criteria (authors use the term SS, focus on SS, teachers or pre-service teachers as population, quantitative or mixed design, published in indexed journals, written in English or Spanish). The data-chart form used captures definitions, examples, design, sample size, instruments, results, as well as other relevant data. Synthesis was carried out using descriptive statistics, content analysis and text mining techniques. Results. 19 studies published between 2012 and 2021 meet the inclusion criteria. A significant portion did not provide an explicit definition of SS; when they do, they emphasize their “personal” and “social” nature and oppose them to Hard Skills. From the 51 different examples provided, only 5 (communication, team work, critical thinking, problem solving and learning) were present in at least 5 articles. While there were experimental and quasi-experimental approaches, the vast majority used observational cross-sectional design, with sample sizes ranging from 13 to 1366 subjects. The use of ad hoc instruments is more frequent than the use of standardized or adapted instruments. Results showed promising correlations and outcomes of interventions; however, methodological limitations impose prudence in the interpretation. Conclusion. The literature shows no consensus on definitions and approaches to teachers' SS. Future research faces the challenge to explicitly define them and develop standardized methods to measure them and assess their impact.