In Chapter 2 we noted that different views of mixed ability grouping can often be seen to reflect attachment to different social principles, particularly to principles of justice and equality. In this chapter the intention is to examine rather more closely ideas of justice and equality and to see if any justifiable connection can be made between justice and/or equality on the one hand and mixed ability grouping on the other. The word 'justifiable' is worth emphasising since we do not find the problem of justification normally pursued as far as it might be in the available literature discussing possible rationales for mixed ability grouping. It is one thing to note, as we have done, the various ways in which views about mixed ability grouping appear to be rooted in ideas of justice and equality; it is quite another thing to present justifications for either the connections or the underlying ideas, and when such justificatory arguments are offered they are sometimes rather weak.