Prof Petal Petersen Williams is employed as a Specialist Scientist in the Mental Health, Alcohol, Substance Use and Tobacco Research Unit (MASTRU) of the South African Medical Research Council. She has a PhD in Public Health and Family Medicine from the University of Cape Town.

She currently holds the position of Associate Professor Extraordinary in the Institute for Life Course Health Research (ILCHR) in the Department of Global Health, Stellenbosch University and Honorary Research Associate in the Department of Psychiatry and Mental Health at UCT. 

She has been involved in a variety of studies including interventions targeting the interface between substance use and HIV, exploration of substance use among pregnant women, treatment service quality, alcohol policy and other substance-related interventions situated within health care settings and worked closely with the Western Cape Department of Health on some of these initiatives. Prof Petersen Williams serves on the editorial board for PLOS ONE.

Her current research focuses on alcohol prevention in pregnant and lactating women and alcohol-related trauma and injury surveillance.