Purpose: To develop an instrument to measure socioeconomic status (SES) in order to assess SES-related inequalities in oral health in a developing country. Materials and Methods: In order to develop a SES measurement tool, an expert panel generated a primary item pool from which the items were revised after validity and reliability testing. The final instrument was used in a 1100-sample survey in Tehran. SES was calculated using the weights produced by both principal component analysis (PCA) and expert panel two-stage paired comparisons (TSPC) methods. Results: The final instrument contained 10 items. Standardised SES scores derived from TSPC and PCA methods were significantly correlated (r = 0.749, P 0.001). Five-level SES stratification by the two methods revealed a correlation coefficient of 0.701 (P 0.001) for SES class. Conclusion: The newly developed SES index was appropriate to be used in exploring oral health inequalities in the studied sample of the Iranian population. When formulating SES, domestic experts' opinions could help the researchers explore and weight sub-construct factors. Keywords: developing countries, inequality, oral health, paired comparisons, principal component analysis, socioeconomic status