This study aims to analyse the relationship between the design and implementation of an Advanced Certificate in Education (ACE) in Mathematical Literacy (ML) (reskilling) program and the development of teacher identities. This study confirms that teacher learning in an in‐service context is a social process that demands a social‐cultural perspective and therefore Wenger’s theory was used in this study. This study illustrates that teachers’ participation in an ACE ML community of practice involved the complex intersection of various components of learning: meaning (learning as experience), practice (learning as doing) and community (learning as belonging) when development of teacher identities takes place. The course was also designed in such a way as to promote a changing way of being. The emerging identities were different in each individual as identity is influenced by the past, the present and the future according to Wenger. The study reveals that when meaning of the subject ML is gained, the meaning can be translated into changed classroom practice. These result in fostering a specific identity influenced by the ACE ML course’s attempts to support the development of understanding in relation to the meaning of ML. This leads to a change in classroom practice and ultimately a change in teachers’ way of ‘being’. This resonates with Wenger’s claim that the four learning components are deeply interconnected and mutually defined. The new trajectories that teachers developed can be grouped into three categories: • Where teachers back grounded their previous identities and fore grounded their ML identities. • Where the teachers added their ML identity to their existing identity, leaving them with a dual identity, the one they had before their involvement in the ACE ML course and the ML identity. • Where those teachers whose existing identity stayed strong, and their ML identity was still developing or was less strong.