Self-development is a crucial aspect of language teaching as it fosters various dimensions of language teacher cognition, affect, and identity, ultimately contributing to better learning outcomes. Most studies on language teacher self-development have examined language teachers' cognitive, affective, and identity-related reactions to particular programmes, often exploring variables in isolation. They have also rarely investigated the self-development practices teachers undertake to support their language teaching ability (LTA). This article reports the findings from a quantitative study on the self-development practices implemented by 113 foreign language teachers of English, French, German, and Spanish in tertiary education to sustain and augment their LTA. Adopting a complex dynamic systems approach, the study employed an online questionnaire to ascertain how variables such as participants' anxiety, beliefs about the status enjoyed by their taught languages among the university administration, colleagues, and society, multilingualism, study and teaching abroad experiences, education level, and interaction mindsets influenced their LTA-related self-development practices. The findings revealed that only participants' interaction mindsets statistically significantly predicted such practices. The article discusses the implications of these results for teacher educators, researchers, and educational institutions, and provides recommendations for the way forward.