Existing instruments for assessing health literacy skills in parents have limited scope to inform the design and evaluation of health literacy interventions. In this study we aimed to develop and validate a new performance-based measure of health literacy for Australian parents, the Parenting Plus Skills Index (PPSI). The instrument aimed to assess functional, communicative and critical health literacy skills.The PPSI was developed in three phases: 1) Modified Delphi Expert Panel to provide feedback on 34 initial items; 2) Evaluation of psychometric properties of each item using a multidimensional item response theory model in a sample of Australian adults of parenting age (20-44 years) (N = 500); 3) Assessment of subset of items in an independent sample (N = 500).Following the three phases, 13 items were included in the final instrument. Participants scored on average 8.9/13 (69 %). The instrument demonstrated acceptable reliability (r = 0.70) and was significantly correlated with other performance-based health literacy instruments.The PPSI is a validated 13-item performance-based instrument that assesses health literacy skills for parents in an Australian setting.The PPSI fills an important gap in available health literacy instruments that may be useful for facilitating development and evaluation of health literacy interventions.