This chapter discusses a capability assessment methodology for cybersecurity training platforms. We first provide an overview of capability assessment, presenting the motivation and background for this approach, as well as defining the relevant stakeholders and their perspectives. The actual capability assessment methodology is introduced next, with a detailed description of the assessment criteria—which are grouped into three categories, training content representation, network environment management, and training activity facilitation—and explain the assessment procedure. Last, we present the capability assessment results for the CyTrONE training framework, which has a total capability level of 71%, examining in detail the results for each criterion category. We also illustrate the interpretation and potential manners of using the capability assessment results from the perspective of the stakeholders defined previously.