Involving teachers in early stages of context-based curriculum innovations requires a professional development programme that actively engages teachers in the design of new context-based units. This study considers the implementation of a teacher professional development framework aiming to investigate processes of professional development. The framework is based on Galperin's theory of the internalisation of actions and it is operationalised into a professional development programme to empower chemistry teachers for designing new context-based units. The programme consists of the teaching of an educative context-based unit, followed by the designing of an outline of a new context-based unit. Six experienced chemistry teachers participated in the instructional meetings and practical teaching in their respective classrooms. Data were obtained from meetings, classroom discussions, and observations. The findings indicated that teachers became only partially empowered for designing a new context-based chemistry unit. Moreover, the process of professional development leading to teachers' empowerment was not carried out as intended. It is concluded that the elaboration of the framework needs improvement. The implications for a new programme are discussed. (Contains 2 figures, 3 tables, and 1 footnote.)