The Essential Dictionary of Music by Lindsey C. Harnsberger is an useful, pocket-sized music handbook for students and professionals. The table of contents shows the 336 page book divided into the following sections: Abbreviations, Pronunciations, Definitions, Composers, Theory and Instruments & Vocal Ranges.

From abandono to Zwischenspiel, the large alphabetized Definitions portion of the book comprises 144 pages. In addition to a strict definition and the source language of the word, each listing includes the foreign language-corrected phonetic pronunciation.

The Composers section lists all important composers with each composer's listing including; Birthdate, Death date (if deceased); Historical Period i.e. "Romantic","Modern" "Baroque" etc.; Compositional Media which is to say in what context(s) their music was written for, performed by and enjoyed by, i.e. orchestra, chamber music, opera etc.; and finally the category Important Items outlines the composers most important contribution to music history and evolution. e.g. under J.S. Bach this reads: "One of the most important and influential composers in the history of music who mastered the composition of contrapuntal music".

The next section is called Theory and provides a compendium of musical theory information such as notes and note relationships, scales, Circle of Fifths, key signatures, chords, dynamic marks, ornaments, notations, music symbols, etc. The final section is Instrument & Vocal Ranges that includes all the instruments of the orchestra as well as all the different male and female voices with their perspective useful playing and singing ranges notated.