Although titled Orchestration, this tome is more instrumentation than orchestration. Forsyth goes into considerable detail with regards to how the different instruments of the orchestra work and what they are capable of, as opposed to how they are used in an orchestral context, which is mostly implied. Copious examples are provided throughout the book from classical repertoire, though given the original publishing date, these do not include anything composed after 1914.

Forsyth also includes many instruments rarely composed for, either due to rarity or to obsolescence, such as less common transpositions or antiquated instruments. This thoroughness is appreciated however, as they contribute not just to completeness, but to the overall theory of the various instrument types.

Throughout the book, Forsyth speaks in an irreverent tone, especially for the period, and will often discuss at length topics for which he is passionate, especially when he dislikes something. Following the initial printing, he even begrudgingly included an additional chapter on the highland bagpipes, having received a letter from a reader who was offended by their initial exclusion.