The paper conducts an empirical analysis of the importance of entrepreneurship for wealth concentration and mobility using data from the Panel Study of Income Dynamics. The data shows a marked concentration of wealth in the hands of entrepreneurs which is not merely a consequence of their higher incomes.  The higher saving rates among entrepreneurs is one of the possible explanations for their higher asset holdings and this hypothesis is supported by the statistical tests conducted in the paper. The data also shows that entrepreneurs experience greater upward mobility in that they have a greater probability of moving to higher wealth classes and, as for the higher asset holdings, this is not only a consequence of their higher incomes.