The Bobbsey Twins was a series of books attributed to Laura Lee Hope, with 72 titles (22 of which were eventually revised) published between 1904 and 1979. Volumes 1–2 were initially published by the Mershon Company (New York) and Volume by Chatterton-Peck (New York), but the remaining titles (and reprints of the first three volumes) were published in hardcover by Grosset and Dunlap. Revised and abridged versions of Volumes 1–13 appeared from 1989 to 1991, with new illustrations by Pepe Gonzalez (Volumes 1–8) and Laurie Harden (10–13). Revised editions from the mid-1950s to the mid-1960s of Volumes 1–12 were reissued as “classic editions” in 2004.
Following the move of Stratemeyer Syndicate titles from Grosset and Dunlap to Simon and Schuster in 1979, the series was rebooted in 1980, with a new series consisting of 14 titles; this series was followed by The New Bobbsey Twins (1987–1992). A short-lived follow-up series appeared in 2005, along with a seven-volume “Ready-to-Read” series.
1. The Bobbsey Twins; or, Merry Days Indoors and Out (1904; revised edition 1928; revised edition [The Bobbsey Twins] 1950; revised edition [The Bobbsey Twins of Lakeport] 1961, reissued 2004; revised edition 1989)
2. The Bobbsey Twins in the Country (1904; revised edition 1950; revised edition [The Bobbsey Twins’ Adventure in the Country] 1961, reissued 2004; revised edition 1989)
3. The Bobbsey Twins at the Seashore (1907; revised edition 1950; revised edition [The Bobbsey Twins’ Secret at the Seashore] 1962, reissued [The Bobbsey Twins: Secret at the Seashore] 2004; revised edition 1989)
4. The Bobbsey Twins at School (1913; revised edition [The Bobbsey Twins and the Mystery at School] 1962, reissued 2004; revised edition 1989)
5. The Bobbsey Twins at Snow Lodge (1913; revised edition [The Bobbsey Twins and the Mystery at Snow Lodge] 1960, reissued 2004; revised edition 1990)
6. The Bobbsey Twins on a Houseboat (1915; revised edition 1955, reissued 2004; revised edition 1990)
7. The Bobbsey Twins at Meadow Brook (1915; revised edition [The Bobbsey Twins’ Mystery at Meadowbrook] 1963, reissued 2004; revised edition 1990)
8. The Bobbsey Twins at Home (1916; revised edition [The Bobbsey Twins’ Big Adventure at Home] 1960, reissued 2004; revised edition 1990)
9. The Bobbsey Twins in a Great City (1917; revised edition [The Bobbsey Twins’ Search in the Great City] 1960, reissued 2004; revised edition 1990)
10. The Bobbsey Twins on Blueberry Island (1917; revised edition 1959, reissued 2004; revised edition 1991)
11. The Bobbsey Twins on the Deep Blue Sea (1918; revised edition [The Bobbsey Twins’ Mystery on the Deep Blue Sea] 1965, reissued 2004; revised edition 1991)
12. The Bobbsey Twins in Washington (1919; revised edition [The Bobbsey Twins’ Adventure in Washington] 1963, reissued 2004; revised edition 1991)
13. The Bobbsey Twins in the Great West (1920; revised edition [The Bobbsey Twins’ Visit to the Great West] 1966; revised edition 1991)
14. The Bobbsey Twins at Cedar Camp (1921; revised edition [The Bobbsey Twins and the Cedar Camp Mystery] 1967)
15. The Bobbsey Twins at the Country Fair (1922; revised edition [The Bobbsey Twins and the County Fair Mystery] 1960)
16. The Bobbsey Twins Camping Out (1923; revised edition 1955)
17. The Bobbsey Twins and Baby May (1924; revised edition [The Bobbsey Twins’ Adventures with Baby May] 1968)
18. The Bobbsey Twins Keeping House (1925; revised edition [The Bobbsey Twins and the Play House Secret] 1968)
19. The Bobbsey Twins at Cloverbank (1926; revised edition [The Bobbsey Twins and the Four-Leaf Clover Mystery] 1968)
20. The Bobbsey Twins at Cherry Corners (1927; revised edition [The Bobbsey Twins’ Mystery at Cherry Corners] 1971)
21. The Bobbsey Twins and Their Schoolmates (1928)
22. The Bobbsey Twins Treasure Hunting (1929)
23. The Bobbsey Twins at Spruce Lake (1930)
24. The Bobbsey Twins’ Wonderful Secret (1931; revised edition [The Bobbsey Twins’ Wonderful Winter Secret] 1962)
25. The Bobbsey Twins at the Circus (1932; revised edition [The Bobbsey Twins and the Circus Surprise] 1960)
26. The Bobbsey Twins on an Airplane Trip (1933)
27. The Bobbsey Twins Solve a Mystery (1934)
28. The Bobbsey Twins on a Ranch (1935)
29. The Bobbsey Twins in Eskimo Land (1936)
30. The Bobbsey Twins in a Radio Play (1937)
31. The Bobbsey Twins at Windmill Cottage (1938)
32. The Bobbsey Twins at Lighthouse Point (1939)
33. The Bobbsey Twins at Indian Hollow (1940)
34. The Bobbsey Twins at the Ice Carnival (1941)
35. The Bobbsey Twins in the Land of Cotton (1942)
36. The Bobbsey Twins in Echo Valley (1943)
37. The Bobbsey Twins on the Pony Trail (1944)
38. The Bobbsey Twins at Mystery Mansion (1945)
39. The Bobbsey Twins at Sugar Maple Hill (1946)
40. The Bobbsey Twins in Mexico (1947)
41. The Bobbsey Twins’ Toy Shop (1948)
42. The Bobbsey Twins in Tulip Land (1949)
43. The Bobbsey Twins in Rainbow Valley (1950)
44. The Bobbsey Twins’ Own Little Railroad (1951)
45. The Bobbsey Twins at Whitesail Harbor (1952)
46. The Bobbsey Twins and the Horseshoe Riddle (1953)
47. The Bobbsey Twins at Big Bear Pond (1953)
48. The Bobbsey Twins on a Bicycle Trip (1954)
49. The Bobbsey Twins’ Own Little Ferryboat (1956)
50. The Bobbsey Twins at Pilgrim Rock (1957)
51. The Bobbsey Twins’ Forest Adventure (1958)
52. The Bobbsey Twins at London Tower (1959)
53. The Bobbsey Twins in the Mystery Cave (1960)
54. The Bobbsey Twins in Volcano Land (1961)
55. The Bobbsey Twins and the Goldfish Mystery (1962)
56. The Bobbsey Twins and the Big River Mystery (1963)
57. The Bobbsey Twins and the Greek Hat Mystery (1964)
58. The Bobbsey Twins’ Search for the Green Rooster (1965)
59. The Bobbsey Twins and Their Camel Adventure (1966)
60. The Bobbsey Twins’ Mystery of the King’s Puppet (1967)
61. The Bobbsey Twins and the Secret of Candy Castle (1968)
62. The Bobbsey Twins and the Doodlebug Mystery (1969)
63. The Bobbsey Twins and the Talking Fox Mystery (1970)
64. The Red, White, and Blue Mystery (1971)
65. The Bobbsey Twins: Dr. Funnybone’s Secret (1972)
66. The Bobbsey Twins and the Tagalong Giraffe (1973)
67. The Bobbsey Twins and the Flying Clown (1974)
68. The Bobbsey Twins on the Sun-Moon Cruise (1975)
69. The Bobbsey Twins: The Freedom Bell Mystery (1976)
70. The Bobbsey Twins and the Smoky Mountain Mystery (1977)
71. The Bobbsey Twins in a TV Mystery Show (1978)
72. The Bobbsey Twins: The Coral Turtle Mystery (1979)