Background Infectious diseases cause considerable morbidity and mortality in children less than 5 years of age. Children attending childcare centres are at increased risk of contracting infections. It is of public health interest to understand what triggers and underpins parental decisions to send an unwell child to childcare, with the obvious attendant risks to other children and childcare staff as well as the affected child. This study aimed to examine parents' disease prevention health beliefs and practices with a particular focus on how these factors influence childcare attendance decisions. Methods Semistructured, in‐depth interviews were conducted between June 2009 and May 2011 with parents who had at least one child under 5 years of age enrolled in a childcare centre. Six centres in the metropolitan area of Sydney, Australia, were selected to include parents from a range of demographic and socio‐economic backgrounds. Results Forty‐two interviews were conducted, recorded, and transcribed. Themes emerging from the data included “vitamin dirt,” contagion, and contagion prevention and control. These interacted with parents' decision‐making about childcare attendance, and parents made choices in a complex context of obligations to their child, social contract obligations to others, peer expectations, and the need to work. Vaccination received only scant mention as a preventive health measure. Decision‐making by parents concerning childcare attendance was made without reference to any external guidelines. Conclusions This study provides insights into parental disease prevention beliefs, behaviours, and decision‐making. It reveals a need for policies to support parents with unwell children. In addition, resources and educative efforts to raise awareness of vaccination as a preventive health measure, and awareness of infectious disease contagion more broadly, would assist in providing parents with a greater evidence base for making decisions about childcare attendance when their child is unwell.