In the article the theoretical framework of public school teachers' continuing professional development (CPD) in Great Britain, Canada and the USA has been presented. The main objectives have been defined as theoretical analysis of scientific and pedagogical literature, which highlights different aspects of the problem under research; presentation and characteristic of two models: the model of unification and the model of diversification of teachers' professional development in the systems of continuing pedagogical education of Great Britain, Canada and the USA by the dominant traits. Their major components have been defined and specified. Public school teachers' CPD has been studied by foreign and domestic scientists: content of public school teachers' CPD (N. Dana Fichtman, M. Rees, A. Ross, S. Zepeda); CPD programs (C. Pratt); public school teachers' CPD models, methods and forms (K. Duinlan, P. Grimmet, G. Troia, P. Wong); continuous professional education (Ya. Belmaz, ?. Kuzminskyy, O. Kuznyetsova). The research methodology comprises theoretical (logical, induction and deduction, comparison and compatibility, structural and systematic, analysis and synthesis) and applied (observations, questioning and interviewing) methods. The research results have been presented.