Many theorists hold that there is, among value concepts, a fundamental distinction between thin ones and thick ones. Among thin ones are concepts like good and right. Among concepts that have been regarded as thick are discretion, caution, enterprise, industry, assiduity, frugality, economy, good sense, prudence, discernment, treachery, promise, brutality, courage, coward, lie, gratitude, lewd, perverted, rude, glorious, graceful, exploited, and, of course, many others. Roughly speaking, thick concepts are value concepts with significant descriptive content. I will discuss a number of problems having to do with how best to understand the notion of a thick concept. Thick concepts have been widely discussed in the metaethical literature. But some important problems concerning what thick concepts are supposed to be have not been squarely addressed even in the most systematic of these discussions. Here I want to highlight these problems.