Teachers' beliefs in their ability to positively impact students' learning outcomes has become a strong indicator of teachers' motivation and behaviour towards the instructional strategies they employ. However, measuring the broader concept of teacher self-efficacy is still somewhat problematic as current scales are dated, have measurement problems, and are not theoretically sound. This paper proposes a new theoretically and rigorously developed scale of teacher self-efficacy that meets current teaching standards and is validated and tested through two phases. This new teacher self-efficacy scale will hopefully greatly facilitate and advance this elusive theoretical construct.