An expandable wall storage system designed to provide maximum storage without loss of floor space. The system provides functional storage for bulky items on top, the flexibility to hang items below and the ability to see what is on the shelf through a gridded shelf. The system includes an interface defined by side portions and at least two support brackets of the storage system for engaging an adjacent expandable wall storage system when aligned in a side-by-side relationship. The system allows easy installation and avoids struggles with overhead mounting. The system can be provided in multiple length configurations and further extensions can also be provided.