The authors study the internal organization of small business partnerships and focus on the number of owners and ownership structure and the dynamics of these variables. They find that partnerships tend to have a small number of owners with equal distribution of ownership shares. Moreover, while partnerships with equally distributed shares tend to keep this distribution constant, those with unequally distributed shares tend to move toward more equal distribution over time. The authors highlight that these facts are in line with the theory of private information in small business partnerships proposed by Espino, Kozlowski, and Sánchez (2014).