In this presentation, we demonstrate the capabilities of CMD to determine the onset of structural transitions in condensed matter by analyzing the thermodynamic (heterogeneously nucleated) and mechanical (homogeneously nucleated) melting of crystalline silicon, as well as stress-induced structural transitions in crystals under hydrostatic loading. In the study of melting, we reconstruct the underlying effective free-energy landscape and calculate the effective free energy difference between the molten and solid states as a function of temperature; in conjunction with a phase coexistence criterion, this leads to an efficient and accurate determination of the melting temperature (as compared with predictions from long MD simulations). In the study of stress-induced structural transformations, we also obtain the effective free-energy landscape and determine its relation to the structural stability of the corresponding solid phases. We focus on bcc → hcp lattice transformations and aim at identifying the loading conditions that mark the onset of such transformations. We demonstrate that the CMD approach is quite general and may be helpful in determining other important types of structural-transition onsets in condensed matter, including order-to-disorder (e.g., solid-state amorphization) and disorder-to-order (e.g., crystallization) transitions. Selecting appropriate coarse-grained variables is crucial to the success of this approach; in this presentation, special emphasis is placed on the choice of such variables in the structural-transition problems analyzed.