In his book Collected Thoughts on Teaching and Learning, Creativity, and Horn Performance, Douglas Hill begins the chapter titled “Horn Duets Reviewed” with the following statement.

Duets are a wonderful and practical way for just two individuals to experience the challenges and joys of chamber music. They can serve as effective tools for teachers to share more than just words with their students. Duets can also help to build better section players by focusing on ensemble, intonation, blend, and articulation. And they are fun! [p. 162]

I agree completely, and have many fond memories of playing duets with teachers and fellow students at almost every level of my musical education. Doug’s reviews are very thorough, and many of the collections he lists are among my favorites too. Since the publication of Collected Thoughts in 2001, I’ve come across some newer publications to add to the list. As with the standards included in Collected Thoughts, these newer duet collections cover a wide range of difficulties and styles, and are highly recommend for use in lessons.

1. Just for Two: Jazz, Vince Gassi, Eighth Note Publications, 2008 This collection belongs to a series of duet collections in jazz style, and according to the composer has “been transposed into keys that are more suitable for horn players at this level.”  That being said, some of the writing, particularly for the 1st part, emphasizes the upper register, and both parts can be quite challenging rhythmically. When it comes to interpreting jazz rhythm and style, horn players are often far less experienced than their colleagues in the trumpet and trombone sections. These duets can aid horn players in developing a more informed approach to jazz phrasing and inflection.
2. Long Tone Duets,David Vining, Mountain Peak Music, 2011 One of my favorite newer collections, I use these duets regularly in lessons, especially with younger students. For a more extensive review, see this post. 
3. Music for Two: Duets in a Jazzy & Classical Style, Various composers, Last Resort Music Publishing, 2001 This eclectic collection features the work of several Los Angeles-based composers, including the legendary studio horn player James Thatcher. As you might guess, much of the music is influenced by film and television scores. The writing can be challenging in places, and many of the pieces could be used to provide variety on recitals or other concerts.
4. Progressive Duets, composed and arr. Larry Clark, Carl Fischer, 2006 This very nice two-volume collection covers easy to advanced difficulty levels, and I particularly like using the easier duets found in Volume 1 with younger students. Arrangements include music from J.S. Bach and Telemann to Franck and Tchaikovsky, to name a few.
5. Seventeen Horn Duets,arr. Marvin Howe, The Hornists’ Nest, 1980 The oldest collection of those listed here, these short works are still musically satisfying. Marvin Howe writes that these duets “were selected in 1973-75 as melodic material for my student, Wesley Yard. The second horn parts were improvised at his lessons, and later notated at his request…The author hopes that these perhaps deceptively simple duets will bring enjoyment to all young horn players, ages 12 to 92.”
6. Ultimate Horn Technique, ed. John Ericson, Horn Notes Edition, 2011 I’ve reviewed this excellent publication here, but thought it was worth mentioning again because of the intonation duets found in the appendix. Though not intended to be as melodically interesting or stylistically diverse as the previous collections, these duets can still be used for effective instruction in lessons or small ensembles. One suggestion when playing these duets is to have a CD or electronic tuner sound a tonic drone for reference.

Do you have some favorite duet collections not listed here or in Doug’s book? Feel free to comment below.