This study sought to examine the kinds of mindsets that the participating teachers demonstrated in their teaching and the impact of teachers' mindsets on their ways of teaching mathematics and science. Seven teachers who were teaching science or mathematics in high-needs schools in the urban context of the Bronx, New York were the participants of the study, with interview data and analysis provided for three participants representing the low, medium, and high mindset groupings. Qualitative research method was used to analyze the data. The data were collected through three different questionnaires, lesson observations, and interviews. Data analysis revealed that six participating teachers demonstrated a growth mindset with different degrees and one teacher seemed to have a fixed mindset. Teachers with a growth mindset adopted instructional practices that are more aligned with those that are recommended in the growth mindset literature.