Appropriate measurement of socioeconomic status (SES) in health research can be problematic. Conventional SES measures based on 'objective' indicators such as income, education, or occupation may have questionable validity in certain populations. The objective of this investigation was to determine if a relatively new measurement of SES, subjective social status (SSS), was more consistently and strongly associated with multiple health outcomes for low income mothers. Data available from a large scale community-based study examining maternal and infant health for a low income urban population were used to examine relationships between SSS and a wide range of postpartum physical and emotional health outcomes. Crosstabulations and multivariate analyses focused on the breadth and depth of these relationships; in addition, the relative strength of the relationships between SSS and the health outcomes was compared to that of conventional measures of SES, including both income and education. SSS was significantly related to all physical and emotional health outcomes examined. The overall pattern of findings indicated that these relationships were independent of, as well as more consistent and stronger than, those between conventional measures of SES and postpartum health outcomes. SSS represents an important dimension of the relationship between SES and postpartum physical and emotional health. In low income populations the failure to account for this dimension likely underestimates the influence of SES on postpartum health. This has important implications for the interpretation of findings in empirical studies which seek to control for the effects of SES on maternal health outcomes.