Yes, you can sort your Zotero library and individual collections within it alphabetically, numerically, and chronologically, in ascending or descending order, by various fields. You can choose the sort field by clicking on the column heading, such as “Title” or “Creator”, at the top of Zotero's center pane. Click again on the same heading to reverse the sort direction.

You can add additional sortable columns by clicking the spreadsheet icon above the vertical scrollbar and choosing from the menu of fields, including “Date,” “Type,” “Year,” and “Publisher”. Your selections will be added to the top of the center pane alongside the other column headings. You can re-order a column by dragging its column heading to the left or right of its original position.

Also note that Zotero sorts by Creator, Date, and Date Modified after the main sort column. For example, if you were to specify “Title” as the primary sort field, and your library contained three or more references with the same title, then Zotero would secondarily sort those items by creator.

A word about how Date and Year work: While Zotero accepts a free-form date in the Date field for each bibliographic record (“Summer 2006”, “Jan 21, 2007”, etc.), the entered value is parsed into recognizable parts (“2006-00-00”, “2007-01-21”, etc.), and these parts are used to sort the field in the middle pane. You can hover over the saved date field to view the parsed date. The Year column also uses the Date field, but only the year portion of it.

View the Sorting Screencast for a demonstration of Zotero's sorting capabilities.