LaTeX users sometimes need to ensure that two or more blocks of text occupy the same amount of horizontal space on the page. To that end, the eqparbox package defines a new command, \eqparbox, which works just like \parbox, except that instead of specifying a width, one specifies a tag. All eqparboxes with the same tag---regardless of where they are in the document---will stretch to fit the widest eqparbox with that tag. This simple, equal-width mechanism can be used for a variety of alignment purposes, as is evidenced by the examples in eqparbox's documentation. Various derivatives of \eqparbox are also provided.