The 2019 Kenya Violence Against Children Survey highlighted the increased prevalence of sexual violence experienced by girls; 62.6% of girls who have experienced childhood sexual violence reported multiple incidents before age 18. Studies have shown that transactional sex (TS) relationships are a source of sexual violence, particularly age-disparate TS. TS is defined as sex that is a nonmarital, noncommercial relationship driven by the assumption that sex is exchanged for material support or other benefits. TS is common among adolescents and young women in sub-Saharan Africa, with the prevalence varying from as low as 5% to as high as 80%. This qualitative study explored the factors influencing age-disparate TS relationships in two rural districts, Mutomo and Ikutha Wards of Kitui South Sub County, Kenya. Four focus group discussions were conducted with primary (12–14 years of age) and secondary schoolgirls (15–18 years of age). The study results identified several main themes, which were grouped into two major themes: influencing factors and consequences. Influencing factors include material/basic needs, school-related influences, parental influence, peer pressure, and perpetrator access, while consequences include health and social consequences. Our study found that girls' sense of agency, social pressure, and economic vulnerability impacted their decision to engage in age-disparate TS. These relationships' power dynamics and exploitative nature increase girls' risk of experiencing gender-based sexual violence and adverse health and social outcomes. Our study suggests that explicitly addressing individual risk behaviors will not effectively reduce the incidence of TS relationships. Interventions should be focused on understanding the social-cultural beliefs of TS and shifting the narrative that has continued to fuel a patriarchal society in which women and girls have limited decision-making power in relationships. [ABSTRACT FROM AUTHOR]