Assessing States’ industrial infrastructure, resources, and capabilities is important for supporting IAEA safeguards activities, such as acquisition path analysis, estimation of lead times to construct new nuclear fuel cycle (NFC) facilities clandestinely, and for building a foundation for understanding the overall picture of a State’s nuclear fuel cycle and nuclear-related programs. The IAEA has been assessing States’ industrial capabilities since the early 2000s, shortly after it began conducting structured state evaluation as part of the earliest implementation of the State Level Concept. Over the years, the IAEA’s methodology for assessing States’ industrial capabilities evolved alongside the State evaluation process. As the IAEA gained access to better information sources and analytical tools, and prioritized training on analytical methodologies, its approach to assessing States’ industrial capabilities became more rigorous, more systematic, and objectives-oriented. Reflecting on the IAEA’s approach to conducting industrial capabilities assessments, this paper reconsiders what the terms “industrial” and “capability” mean in different contexts. How these terms are defined dictate what activities are included and what technical proficiencies are taken into account when doing an industrial capabilities assessment. The paper argues that different safeguards evaluation objectives require focusing on different levels of State technical proficiency, and it demonstrates how both narrow and broad definitions of these terms could assist in conducting more efficient and effective analysis of States’ industrial capabilities.