There is a well-established area of work in mathematics education focusing on mathematics for social justice. Much of the work, however, is concerned with "individual" students' understanding the world symbolically -- as evident in the notions of reading and writing the world using mathematics -- while failing to address a transformative agenda that seeks to make a positive difference in a once-occurrent world that we inhabit together with others as part of our once-occurrent lives. In this conceptual essay, we describe and exemplify a transactional approach that inherently is a practical approach. In the transactional approach, the individual is not merely agent but importantly subject to and constituted by social processes that transform the world including the self.