|
| O Sing unto the Lord a New Song, No.2 | D. J. Becker; David J. Becker | David J. Becker | Detroit Lakes, Minn. | 1941 | | | 19 | |
| Oak Leaf Collection of Junior Chorales | L. Rhea; Edwin H. Morris & Co. | Edwin H. Morris & Co. | New York, N.Y. | 1951 | | | 5 | |
| Oberlin social & sabbath school hymn book | Allen, George N | James N. Fitch | Oberlin | 1846 | | | 221 |  |
| Ocean Grove Christian Songs: "The Big Little Book" | The Ocean Groove Association: Tali Esen Morgan; Bishop J. A. Fitzgerald | Tali Esen Morgan | Ocean Grove, N.J. | 1902 | Methodist hymnals (general) | Has Music | 170 |  |
| Ocean Grove Songs | Bishop J. N. Fitzgerald; Rev. Chas. H. Yatman; Tali Esen Morgan; Ocean Grove Association | Ocean Grove Association | Ocean Grove, N. J. | 1900 | Methodist Church | Has Music | 164 |  |
| Ocean Melodies, and Seamen's Companion: a collection of hymns and music; for the use of Bethels, Chaplains of the Navy and private devotion of Mariners | Phineas Stow | Phineas Stow | Boston | 1849 | Baptist hymnals (general) | Has Music | 379 |  |
| Offering of Praise | J. L. Hall; C. A. Miles; Hall Mack Co. | Hall Mack Co. | Philadelphia, Penn. | 1911 | | | 224 | |
| Offices of Worship and Hymns: principally for use in schools. with an appendix of tunes (2nd and rev. ed.) | Moravian Pub. Office | Moravian Pub. Office | Bethlehem, Penn. | 1883 | Moravian Church in America (Unitas Fratrum) | | 389 |  |
| Offices of Worship and Hymns: with tunes, 3rd ed., revised and enlarged | Moravian Publication Office | Moravian Publication Office | Bethlehem, Penn. | 1891 | Moravian Church in America (Unitas Fratrum) | Has Music | 1565 |  |
| Ogle's Praise Hymns and Revivalist | John J. Hood | John J. Hood | Philadelphia, Penn. | 1883 | | | 73 | |
| Okodakiciye Wakan Odowan Qa Okna Ahiyayapi Kta Ho Kin/Hymnal with Tunes and Chants According to the Use of the Episcopal Church in the Missions among the Dakotas | | Midwest-Beach Co. | Sioux Falls, SD | 1951 | Episcopal Church | | 248 | |
| Old and New Songs of the Church | Rodeheaver Co. | Rodeheaver Co. | Chicago, Ill. | 1935 | | | 65 | |
| Old and New Welsh and English Hymns | Cymanfa Ganu | Cymanfa Ganu | Wisconsin | 1939 | | | 333 | |
| Old Camp Meeting Songs | Albert Ott | | Dallas, Tex. | 1940 | | | 183 | |
| Old Choir Selections | Synod of the Maritime Provinces | Synod of the Maritime Provinces | Canada | 1942 | Presbyterian Church in Canada | | 62 | |
| Old Fashioned Revival Hour Songs Compiled | Charles Fuller; Hall Mack Co. | Hall Mack Co. | Winona Lake, Ind. | 1950 | | | 114 | |
| Old Melodies Spiritualized | H. W. Boozer | | Grand Rapids, Mich. | 1896 | | | 54 | |
| Old School Sonnets, or a Selection of Choice Hymns | James Osbourn; John D. Toy | John D. Toy | Baltimore, Md. | 1836 | Primitive (Old School) Baptists | | 340 | |
| Old Time Glory | John T. Benson; John T. Benson Pub. Co. | John T. Benson Pub. Co. | Nashville, Tenn. | 1949 | | Has Music | 139 |  |
| Old Time Revival | John T. Benson; John T. Benson Pub. Co. | John T. Benson Pub. Co. | Nashville, Tenn. | 1950 | | | 133 | |
| Old Time Revival Songs | Alfred E. Smith; Alfred E. Smith | Alfred E. Smith | Wheaton, IL | 1950 | | | 147 | |
| Old-Time White Camp-Meeting Spirituals | Samuel E. Asbury; Henry E. Meyer; Texas Folk-Lore Society Publications | Texas Folk-Lore Society Publications | Austin, Tex. | 1932 | | | 8 | |
| On Wings of Song | George C. Hugg; George C. Hugg | George C. Hugg | Philadelphia, Penn. | 1896 | | | 197 | |
| One Faith, Una Voz | John J. Limb | OCP | Portland, OR | 2005 | Roman Catholic Church | | 1 | |
| One Hundred Favorite Songs of the Salvation Army | Booth-Tucker | | | 1893 | Salvation Army | | 171 | |
| One Hundred Hymns You Ought to Know | Henry Cope; Fleming H. Revell Co. | Fleming H. Revell Co. | Chicago, Ill. | 1906 | | | 96 | |
| One Hundred Non-Sectarian Hymns for Use in Church and Home. 10 vols. in 1 | A. J. Davis; G. Schirmer | G. Schirmer | New York, N.Y. | 1886 | | | 83 | |
| One Hundred Progressive Hymns | Henry B. Ashmead | Henry B. Ashmead | Philadelphia | 1860 | | | 100 |  |
| One Hundred Select Gospel Hymns from Gospel Hymns Consolidated | I. D. Sankey; Biglow & Main Co. | Biglow & Main Co. | Chicago, Ill. | 1883 | | | 95 | |
| One hundred songs of praise: used by Andrew J. Dolbow in his evangelistic services | Dolbow, A. J | John J. Hood | Philadelphia | 1890 | | | 0 |  |
| Onward: a Complete Rally Day Service | Judefind Bros. | Judefind Bros. | Baltimore, Md. | 1911 | | | 11 | |
| Onward and Upward | E. T. Hildebrand; J. D. Vaughan; Home Music Co. | Home Music Co. | Logansport, Ind. | 1898 | | | 110 | |
| Onward and Upward No. 2: a collection of gospel songs and hymns for Sunday-schools, Endeavor societies, Epworth leagues, devotional meetings, chapel exercises, revivals, etc. | W. T. Giffe; E. T. Hildebrand; Home Music Co. | Home Music Co. | Logansport, Ind. | 1900 | | Has Music | 109 |  |
| Open Door, Revival Songs. Rev. ed. | Nathaniel Carlson; Beacon Book Store | Beacon Book Store | Minneapolis, Minn. | 1951 | | | 64 | |
| Open Gates | Fillmore Music House | Fillmore Music House | Cincinnati, Oh. | 1928 | | | 10 | |
| Orders of Worship for the Sunday School | D. E. Curtis; Congregational Sunday School and Publishing Society | Congregational Sunday School and Publishing Society | Boston, Mass. | 1890 | Congregational Christian Churches, 1931- | | 25 | |
| Ordo de Diservo | J. Cyprian Rust (Soham, Cambs.) | La Tria Kongreso | England | 1907 | Church of England | Esperanto | 27 |  |
| Original and Select Hymns, and Sacred Pindoric Odes., few of which have ever been published (1st. ed.) | Paris M. Davis; Jonathan Howe | Jonathan Howe (Printer) | Boston | 1830 | | | 66 |  |
| Original and Selected Reformation Hymns ... dedicated to the Twelve Tribes of the Lord's Modern Israel | Luther Roby | Luther Roby | Concord, N.H. | 1829 | | | 113 | |
| Original Hymns for Sabbath Schools | J. S. W.; Lilly, Wait, Colman, & Holden | Lilly, Wait, Colman, & Holden | Boston | 1833 | | | 57 |  |
| Original Shaker Music | Wm. A. Pond & Company; North Family of Mt. Lebanon, NY | Wm. A. Pond & Company | New York | 1893 | Shakers | Has Music | 219 |  |
| Oriola | W. B. Bradbury; Biglow & Main Co. | Biglow & Main Co. | New York, N.Y. | 1859 | | | 306 | |
| Oriola | W. B. Bradbury; Biglow & Main Co. | Biglow & Main Co. | New York, N.Y. | 1890 | | | 314 | |
| Our Best Endeavor | W. A. Ogden; C. E. Prior; Silver Burdett | Silver Burdett | Boston, Mass. | 1892 | | | 181 | |
| Our Choice | C. H. Gabriel; Pentecostal Pub. Co. | Pentecostal Pub. Co. | Louisville, Ky. | 1913 | | | 224 | |
| Our Church and Revival Songs | David E. Dortch; William G. Cooper; Gospel Winchester Co. | Gospel Winchester Co. | Tullahoma, Tenn. | 1911 | | | 115 | |
| Our Cumberland Presbyterian Hymnal | David E. Dortch; Gospel Winchester Co. | Gospel Winchester Co. | Tullahoma, Tenn. | 1911 | Cumberland Presbyterian Church | | 416 | |
| Our Family Circle | Ernest Dunklee | Dunklee | South Vernon, Mass. | 1950 | Advent Christian Church | | 60 | |
| Our Favorite Hymnal | W. A. Chastain | | Springfield, Ill. | 1938 | Primitive (Old School) Baptists | | 378 | |
| Our Glad Hosanna | R. Lowry; W. H. Doane; Biglow & Main Co. | Biglow & Main Co. | New York, N.Y. | 1882 | | | 325 | |