Becoming a father for the first time might cause great changes in a man’s identity and lifestyle. Teenage fathers must strive to balance two competing roles: the teenage role and the father role. The current study design followed grounded theory methodology to gain a deeper understanding of how Thai teenage fathers reason about becoming and being a father from a gender equality perspective. Participants were selected from a heterogeneous group of fathers until saturation was reached (n = 25). Most of the fathers were cohabiting with their partner in an extended family. An interview guide was developed, a pilot study was undertaken, and interviews were performed on two different occasions: once during the second trimester of pregnancy and again when the baby was 5 to 6 months old. The core category, "Male breadwinners involved in parenting," encompassed persons making the transition from being solely a teenager to being a teenage father. Most of the fathers accepted the unintended pregnancy and took on the expected breadwinning responsibility of a father. They prepared for fatherhood and changed their lifestyle. Their families provided support. Nevertheless, the fathers sought to avoid further unplanned parenthood by learning about family planning. The teenage fathers emphasized breadwinning first, then involved himself in the child and the housework. These findings provide an increased understanding of Thai teenage fathers.