Background: This study was designed to investigate the effectiveness of various training methods for breast self-examination (BSE) knowledge, practice, and health beliefs. Methods: The quasi-experimental investigation was carried out in an area where two community health care centers are located, in the city of Trabzon, Turkey. Divided randomly into three groups, 1,342 women were instructed in BSE using individual or group training or by way of pamphlets. Data were gathered in four stages: during the pretraining and one month, six months, and twelve months after training. Results: All of the training methods used in the study produced a significant increase in the participants' BSE knowledge, but individually trained women scored higher than did the others. Regardless of the training method, BSE instruction improved the women's perceived confidence and benefits, while their perceived barriers declined. The variables influencing BSE practice were found to be BSE practice at the pretraining period, perceived confidence in and benefits from BSE six months after BSE instruction, and health motivation one year after training. No significant difference was found in women's BSE performance scores one year after training. Conclusion: This study in which three training methods were used enabled us to assess the effectiveness of instruction on BSE performance and competence. In addition, it provided us with valuable information on how training methods can influence health beliefs related to BSE.