Background: Psychosocial assessment and depression screening is now recommended for all women who are pregnant or have recently given birth in Australia. Existing studies which have examined the extent of participation by women in such population-based programs have been primarily concerned with depression screening rather than a more comprehensive examination of psychosocial assessment, and have not been sufficiently inclusive of the 30% of women whose maternity care is provided in the private sector. Whether there are disparities in equity of access to perinatal psychosocial assessment is also unknown. Methods. A sub-sample of women (N = 1804) drawn from the Australian Longitudinal Study on Women's Health participated in the study. Overall rates of assessment across five psychosocial domains (current emotional health; mental health history; current level of support; current drug or alcohol use; experience of domestic violence or abuse), as well as receipt of mental health promotion information, were examined. Log binomial regression was performed to investigate whether there were socio-demographic or health system inequalities among women who are and are not assessed across each domain. Results: Two-thirds of women (66.8%) reported being asked about their current emotional health in the antenatal period, increasing to 75.6% of women in the postnatal period. Rates decreased markedly for reported assessment of mental health history (52.9% during pregnancy and 41.2% postnatally). Women were least likely to be asked about their experience of domestic violence or abuse in both the antenatal and postnatal periods (in total, 35.7% and 31.8%, respectively).In terms of equity of access to psychosocial assessment, women who gave birth in the public hospital sector were more likely to report being assessed across all domains of assessment in the antenatal period, compared with women who gave birth in the private sector, after adjusting for other significant covariates. State of residence was associated with reported rates of assessment across all domains in both the antenatal and postnatal periods. Women from non-English speaking backgrounds and women with more than one child were less likely to be assessed across various domains. Conclusion: This study provides an important insight into the reported overall penetration of and access to perinatal psychosocial assessment among a sample of women in Australia. Opportunities to minimise the current shortfall in assessment rates, particularly in the private sector, and for ongoing monitoring of assessment activity at a national level are discussed.