BACKGROUND: Human papillomavirus (HPV) vaccination in adolescents provides a powerful tool for preventing cervical cancer in women and other HPV-associated diseases in people of all genders. HPV vaccines have been progressively introduced in many countries. However, worldwide, many adolescents do not receive HPV vaccination, for various reasons. The HPV vaccine might be costly or unavailable, healthcare systems might lack capacity for its delivery, or adolescent health might not be prioritised. Some caregivers and adolescents may not accept available HPV vaccines and vaccination services. We currently lack a comprehensive understanding of the factors that influence HPV vaccination views and practices, and why some caregivers and adolescents may be less accepting of the vaccine. Qualitative research can contribute to this understanding and help inform policy and practice, including the development of more relevant, acceptable and effective interventions to promote public acceptance and uptake of HPV vaccination in adolescents. This qualitative evidence synthesis supplements a Cochrane review of the effectiveness of interventions to improve uptake of adolescent vaccination, including HPV vaccination. OBJECTIVES: The objectives of the review are to identify, appraise, and synthesise qualitative studies that explore caregivers' or adolescents' views, experiences, practices, intentions, decision-making, acceptance, hesitancy, or nonacceptance of HPV vaccination; to gain an understanding of the factors that influence caregiver and adolescent views and practices regarding HPV vaccination for adolescents; and to explore how the findings of this review can enhance our understanding of the related Cochrane intervention review. SEARCH METHODS: We searched MEDLINE, Embase, CINAHL, PsycInfo, and Scopus for eligible studies (February 2023). We updated this search in October 2024, but these results have not yet been fully incorporated. SELECTION CRITERIA: We included studies that utilised qualitative methods for data collection and analysis; focused on caregivers' or adolescents' views, practices, acceptance, hesitancy, or refusal of HPV vaccination for adolescents aged 9 to 19 years of age; and were from any setting globally where HPV vaccination is provided. DATA COLLECTION AND ANALYSIS: We used a prespecified sampling frame to capture a sample of eligible studies that were from a range of geographical and income-level settings, were conceptually rich in relation to the review's phenomenon of interest, and included HPV vaccination for diverse genders. We extracted contextual and methodological data from each sampled study. We used a thematic synthesis approach to analyse the evidence. We assessed methodological limitations using a list of criteria used in previous Cochrane reviews and originally based on the Critical Appraisal Skills Programme quality assessment tool for qualitative studies. We used the GRADE-CERQual (Confidence in the Evidence from Reviews of Qualitative research) approach to assess our confidence in each review finding. We integrated the findings of this review with those from the related Cochrane review of intervention effectiveness (by Abdullahi and colleagues), by mapping whether the trial interventions reflected or targeted the factors identified by this review as influencing caregivers' or adolescents' views and practices regarding HPV vaccination. MAIN RESULTS: We included 206 studies in the review and sampled 71 of these for our synthesis. Of these, 35 studies were conducted in high-income countries, 26 studies in middle-income countries, 8 studies in low-income countries, and 2 studies in multiple-income settings. Studies came from all six World Health Organization (WHO) regions and included urban and rural settings. We downgraded our confidence in several findings, mainly due to concerns about how the studies were conducted (methodological limitations), concerns about perspectives lacking from some types of participants or in some settings (relevance), or because of variability in the data or insufficient evidence to support all aspects of a review finding (coherence). Many complex factors were found to influence caregivers' and adolescents' HPV vaccination views and practices, which we categorised into eight overarching themes: 1) A lack of biomedical knowledge; 2) Perceptions of a range of interrelated risks and benefits (or lack thereof) associated with HPV vaccination; 3) Routine responses to vaccination generally or more specific views or experiences of other vaccines and vaccination programmes; 4) Complex nuclear familial decision-making dynamics; 5) Extended familial and social relations and networks, particularly extended family members, peers, traditional or religious leaders, and the media; 6) Interrelated socio-cultural beliefs and practices regarding adolescence, sexuality, gender, parenting and health; 7) Trust or distrust in the institutions, systems or experts associated with vaccination, most particularly teachers and the school, the pharmaceutical industry, government, science and biomedicine, and healthcare professionals; and 8) Access to, and experiences of, HPV vaccination programmes and delivery services, such as the convenience (or lack thereof) of HPV vaccination services, the cost of the vaccine, language barriers, the feminisation of HPV vaccination programmes and procedural aspects of school-based vaccination delivery. We did not identify any major differences in the occurrence of these overarching themes between subgroups. However, for various subthemes certain differences emerged in relation to place, gender and socio-economic status, and between caregivers and adolescents. The interventions tested in the related Cochrane review of intervention effectiveness most commonly targeted caregivers' and adolescents' lack of biomedical knowledge and their perceptions of the risks and benefits of HPV vaccination, with the other influencing factors identified by our review being underrepresented. AUTHORS' CONCLUSIONS: Our review reveals that caregivers' and adolescents' HPV vaccination views and practices are not only influenced by issues related to individual knowledge and perceptions of the vaccine, but also an array of more complex, contextual factors and meanings: social, political, economic, structural, and moral. Successful development of interventions to promote the acceptance and uptake of HPV vaccination for adolescents requires an understanding of the context-specific factors that influence HPV vaccination views and practices in the target setting. Through this, more tailored and in turn more relevant, acceptable, and effective responses could be developed. The eight overarching themes that emerged from our review could serve as a basis for gaining this understanding.