This present study sought to explore reasons given by K-12 teachers about their motivation to remain in teaching, their motivation for engaging in professional development, and characteristics of their teaching. Participants (N = 151) were public teachers of different grade levels from the USA enrolled in a one-week professional development training. Respondents' ratings on reasons for continuing teaching revealed that four key-specific factors were the main influences for continuing to teach, namely intrinsic reasons, extrinsic reasons, job perception, and extended reasons. Further analysis indicated that their reasons for teaching were correlated with specific incentives for attending the professional development training, with teachers' instructional beliefs, and with professional development programme outcomes. Study results are discussed in relationship with teaching motivation and implications for teachers' professional growth.