Glass-ceramic composites were developed from mixer slag. The slag-derived glass was produced by adjusting the slag basicity (CaO/SiO2 < 1) and the melting at 1550 degrees C and then quenched in air. The devitrification of the glass was achieved at a temperature of 900 degrees-1100 degrees C. Composites composed mainly of wollastonite, gehlenite, and calcium manganese silicates were crystallized and identified by XRD and confirmed by backscattered SEM-EDX. In addition, anorthite and other composites containing barium were crystallized and disappeared based on the temperature of the heat treatment. Nonisothermal kinetics of the slag-derived glass using differential scanning calorimetry and the analysis of the results using several approaches to determine the activation energy and mechanism of the crystallization were obtained. It was found that the crystallization growth of this kind of glass-ceramic derived from mixer slag occurred by an interface-controlled mechanism rather than a diffusion-controlled mechanism.