We developed a scale to assess teachers' perceptions of group dynamics in schools. The sample consisted of 995 teachers from five public schools affiliated with the Ministry of National Education, Turkey. Construct validity was determined using an exploratory factor analysis (EFA) and a confirmatory factor analysis (CFA). The EFA results revealed a one-factor structure that accounted for 44% of the total variance. The CFA results indicated acceptable goodness of fit indices for the one-factor group dynamics scale (GDS) model. Criterion validity was determined using the scale of organizational silence (SOS) and the person-organization fit scale (POFS). The results showed that the GDS was positively correlated with POFS and negatively correlated with SOS. Reliability was measured on three different samples. The GDS had a Cronbach's alpha ([alpha]: internal consistency coefficient) of 0.88 to 0.89. Reliability was also analyzed using the test-retest method. The results showed that the GDS had an acceptable reliability coefficient. These results indicated that the GDS was a reliable measure. The "upper and lower 27 percent rule" and corrected item-total correlation coefficients were used for item analysis. The former revealed acceptable results for all three samples, while the latter revealed significant t-test results for all items. All these results indicate that the GDS is a valid and reliable measure.