As is clear from the title of the National Income Dynamics Study (NIDS), one of the major reasons for undertaking South Africa's first national panel study has been to gain an understanding of income mobility. In 2008, a nationally sampled set of South African residents were visited for the first time in wave 1 of NIDS. During this visit, the baseline information was gathered to track and understand changes in their well-being going forward. This sample was nationally representative in order for NIDS to provide an assessment of these changes at the aggregate level. Also, it was large enough to enable NIDS to provide information on key sub-sets of this national story. We need to know who is making progress in terms of escaping poverty, or at least increasing their real income and what factors are driving this. Also, we need to know who is persistently poor and why.