An adjustable shelving unit that may be adjusted by increasing or decreasing the width or depth of the unit and may be adjusted to be in either a horizontal orientation or a forward sloping orientation. The adjustable shelving unit may include a central shelf unit and at least one extension shelf unit. The extension shelf unit may be oriented in a sliding manner with respect to the central shelf unit to permit the adjustment of the width or depth of the shelf by extending or retracting the extension shelf unit with respect to the central shelf unit. Attachment members extending from the central shelf unit allow the shelf to be mounted in either a horizontal or a forward sloping orientation.