Put together in 1994 as part of the Utah Centennial celebration, this work is an excellent set of articles on Utah History.
It has over 500 articles covering a wide range of topics including institutions, peoples, movements, individuals and a host of other topics -- providing a wealth of information on Utah history.
Articles are concise and to the point, providing a good introductory article on each topic without becoming wordy, and preventing one from getting bogged down in detail.
The two shortcoming of the encyclopedia are that it contains no history after 1994, and has no bibliographic information for further reading. But these are minor issues.