Background Preschool-aged children are the highest consumers of antibiotics, but consult mainly for viral infections. Little is known about how day care, which is common in this age group, influences primary care consulting and treatment-seeking behaviours. Aim To investigate daycare providers' approaches to excluding and/or readmitting children with infections, and the consequences for parents' consulting and antibiotic-seeking behaviours. Design and setting Cross-sectional survey, document analysis, and qualitative interviews of daycare providers and parents in South East Wales, UK. Method A total of 328 daycare providers were asked to complete a survey about infection exclusion practices and to provide a copy of their sickness exclusion policy. Next, 52 semi-structured interviews were conducted with purposively selected questionnaire responders and parents using their services. Questionnaire responses underwent bivariate analysis, policies underwent document analysis, and interviews were thematically analysed using constant comparison methods. Results In total 217 out of 328 (66%) daycare providers responded; 82 out of 199 (41%) reported advising parents that their child may need antibiotics and 199 out of 214 (93%) reported advising general practice consultations. Interviews confirmed that such advice was routine, and beliefs about antibiotic indications often went against clinical guidelines: 24% (n = 136) of sickness exclusion policies mentioning infections made at least one non-evidence-based indication for 'treatment' or antibiotics. Parent interviews revealed that negotiating daycare requirements lowered thresholds for consulting and encouraged antibiotic seeking. Conclusion Daycare providers encourage parents to consult general practice and seek antibiotics through non-evidence-based policies and practices. Parents' perceptions of daycare providers' requirements override their own beliefs of when it is appropriate to consult and seek treatment. (author abstract)