Does Mendeley support classifying literature into multiple folders?

Yes, Mendeley allows assigning a single reference entry to multiple collections. This functionality provides significant flexibility in organizing literature according to various research themes or project needs beyond a rigid folder hierarchy. References are stored in a central library. The primary organizational mechanism is through user-created Collections, analogous to folders. Crucially, while a reference physically resides only once in the library, it can be linked to multiple Collections simultaneously without duplication. Assigning a reference to additional Collections is done through the right-click context menu or drag-and-drop. However, Mendeley does not support true "subfolders" within Collections; complex nesting requires careful naming or supplementary tagging. Tags offer a complementary organizational layer for cross-cutting attributes. This multi-collection support enables highly adaptable literature management suited to academic research. Key applications include classifying a paper into distinct thematic groupings relevant to different projects, organizing literature reviews by multiple conceptual frameworks, and ensuring relevant papers appear in both methodology-specific and topic-specific Collections. This enhances discoverability, workflow efficiency, and reduces manual redundancy compared to physically copying files.