Substance use is increasingly common in many countries. Consumption and lifestyles associated with consumption often involve a number of specific health and legal risks for users. For pregnant women, the risks extend to the health and care of their unborn children. A multi-professional approach to the management of substance use in pregnancy is recommended as best practice but, as with all strategies, effectiveness depends on the way that professional workers implement policy. This study evaluated evidence of multi-professional working within local maternity services in and around a Scottish city by (a) collating and analysing data from the maternity records of 163 substance-using women, who delivered between January 2001 and December 2003; and (b) conducting a questionnaire survey in 2004 with 120 midwives and neonatal nurses for their views on maternity care for substance-using women and their babies. Despite the importance placed on multi-professional working by midwives and neonatal nurses, maternity records indicated operational inconsistencies with implementation in some cases and not in others. Policy was not yet to be seen embedded in everyday practice.