This study investigates the variables affecting firm profitability applying the seemingly unrelated regression method to a large sample of approximately 87,000 observations covering 12,530 non-financial micro firms operating in four industry sectors from 2006 to 2007. The study considers profitability determinants at the firm as well as industry affiliation levels in examining hypotheses developed from resource-based approaches. The findings indicate that while firm size, lagged profitability, growth, and productivity positively influence profitability, firm age and industry affiliation negatively influence it. The empirical results suggest that productivity is the most significant determinant of profitability. These results are fairly robust across the various industry sectors covered in the study and are largely consistent with the hypotheses developed from the resource-based approach.