The present study was designed to examine the factors that motivate or act as barriers to disclosure of substance use by pregnant women. Participants included 10 midwives and 10 pregnant women who attended two ante-natal clinics at an Australian maternity hospital. One clinic specialized in women who were substance users and one clinic was specifically for young women (under 19 years of age). Midwives and pregnant women were interviewed in-depth about disclosure of substance use. Interview transcripts were analyzed, and the results revealed six main themes: practice style, assessment of substance use, practice environment and privacy, child protection issues, health of the baby, and continuity of care. The findings are discussed in relation to recommendations for best practice in midwifery care when working with pregnant women who use substances.<br /