• Chris Polk - Lead Guitar, Van Dorn Street (Vol. 1)

  • Robinson Lee Earle & Sara Mosher - Acoustic Guitar & Vocals, East Falls Church (Vol. 1)

  • Seth Kibel - Flute, Ice Skating at the Archives (Vol. 2)

  • Matt Slaughter - Chorus Voice, Clarendon (Vol. 2), Drum Machine, Deanwood (Vol. 4)

  • David McLaughlin - Banjo & Mandolin, Tenleytown (Vol. 3)

  • John Simmons - Rickenbacker 12-string, Tenleytown (Vol. 3)

  • The Six Degree Singers, dir. by Rachel Carson - How an Afternoon Dream Caused Her to Miss Her Stop at Silver Spring (Vol. 3)

  • The Williams PipeTone Organ at Congressional Cemetery - Potomac Ave. (Vol. 3)

  • Louis Loman (percussion), Ken Francis Wenzel (sax), Molly Hagen (voice), Rachel Levitin (voice) - Deanwood (Vol. 4)

  • Maureen Andary, Sara Curtin (The Sweater Set) - Lyrics, Vocals, Flute, Ukulele, Bells - Strathmore (Vol. 4)

  • Jonny Grave (slide guitar), Terry Boes (harmonica) - Union Station (Vol. 4)

  • The Blue Angelinas - Blue Angelina I - IV & Twinbrook (Vol. 5)

  • Alissa Moore (violin), Bill Martien (guitar), of Star FK Radium - Stadium/Armory (Vol. 5)

  • Alexander Grushin (poetry) - Twinbrook (Vol. 5)

  • Cathy DiToro (voice) - Prince George's Plaza (Vol. 6)

  • Ken Francis Wenzel (sax) - Prince George's Plaza (Vol. 6)

  • Anders Fahey (banjo) - Spring Hill (Vol. 6)

  • Sam Snow (beats) - Court House (Vol. 6)

  • Ardamus (lyrics & voice) - Shaw (Vol. 6)

  • The Washington Redskins Marching Band - Landover (Vol. 7)

  • Derek Evry (backing voice), Pat Frank (drums), Kevin de Souza (bass) - Tysons Corner (Vol. 7)

  • Dan McNabb from The Beginner’s Mynd (lead 12-string electric guitar) - McLean (Vol. 7)

  • Ms. Fridrich (piano) - Suitland (Vol. 7)

  • Karlin McNeill (verse recitation and bass), Oren Levine (organ), Mort Rolleston (drums), Ian Taronji (guitar) - Anacostia (Vol. 7)

  • The Beanstalk Library and Rachel Levitin - Ballpark (Vol. 7)

  • Faith Hayden and Maryjo Mattea (vocals) - Naylor Road (Vol. 7)

  • Faith Hayden (vocals) - White Flint (Vol. 7)

  • Matthew James Scott (ukulele) - Congress Heights part I

  • Selling Fairfax By The Pound - Congress Heights part II

  • John Mondelli (narration) - Franconia-Springfield (Vol. 8)

  • Faith Hayden (vocals) - Shady Grove (Vol. 8)