The document describes a new instrument called the Multidimensional Measure of Conceptual Complexity (MMCC) that aims to assess students' conceptual understanding of chemical equilibrium. [1] The MMCC measures conceptual understanding across two dimensions - conceptual depth and conceptual breadth. [2] Conceptual depth reflects hierarchical levels of understanding from acausal to emergent, while conceptual breadth reflects the range of phenomena a causal explanation can be applied to. [3] The MMCC aims to locate students within this two-dimensional space of conceptual complexity to provide meaningful measures of their understanding.