A long running series ghostwritten under the pen name of Laura Lee Hope by the Stratemeyer Syndicate which follows the Bobbsey Family, composed of two sets of fraternal twins and their parents. Bert and Nan are the older dark-haired set of twins and Freddie and Flossie are the younger blonde twins. When the first book was written and set in 1903, Bert and Nan were eight years old and Freddie and Flossie four. Seventy-two volumes later, the last book was written and set in 1979 with Bert and Nan having aged to 12 and Freddie and Flossie aged to 6.
- Mr. Richard Bobbsey - owner of a lumber yard in Lakeport.
- Mrs. Mary Bobbsey - his wife.
- Nan Bobbsey - their elder daughter, Bert's twin.
- Bert Bobbsey - their elder son, Nan's twin.
- Freddie Bobbsey - their younger son, Flossie's twin.
- Flossie Bobbsey - their younger daughter, Freddie's twin.
- Dinah Johnson - the Bobbseys' black cook, Sam's wife.
- Sam Johnson - the Bobbseys' man of all work, Dinah's husband.
- Snoop - the Bobbseys' cat, originally a stray kitten befriended and adopted by Freddie.
- Snap - the Bobbseys' first and oldest dog, a retired circus dog.
- Waggo - The Bobbseys' second dog, a highly energetic foxterrier.
- Danny Rugg - a "bad boy."
The books provide examples of:
- Ambiguous Gender: Snoop the cat. One of the more curious parts of the Continuity Drift/Continuity Snarl mentioned below, possibly a case of Writer Gender Confusion, is that Snoop tends to change genders between books. The cat is definitely a male in the first four books, but has suddenly and without explanation become female in the fifth book. In subsequent books the cat switches between being male and female; at one point even switching from male to female within the course of one book, without anyone except the readers noticing.
- As You Know: A peculiar version, as the narrator text sometimes repeats information that the audience already knows, providing recaps of information that happened earlier in the same book. It's especially blatant in the cases of Snoop and Snap — whenever they appear on-page and haven't been mentioned for a while, the narrator almost always makes sure to inform the audiences that they are, in fact, a cat and a dog.
- Flossie and Freddie, especially in earlier books, tend to refer to Snoop as "our cat Snoop" or even "our black cat Snoop" when referring to him to the other members of the family, who should very well know that Snoop is a cat and that he's black. Might be justified in this instance, though, as Flossie and Freddie are small children — it may very well make sense to them to talk like this.
- The Bully: Danny Rugg, though exactly how bullying he is depends on the book. Sometimes he's on fairly civil terms with the Bobbsey twins, sometimes his entire life seems to revolve around playing mean-spirited pranks on them.
- Color-Coded Characters: Nan and Bert are darkhaired and thin. Freddie and Flossie are blonde and chubby.
- Comic-Book Time: As time moves on, the Bobbsey Twins have remained the same age.
- Continuity Drift/Continuity Snarl: About as much as you'd expect for 72 books written over 76 years by dozens of authors. Pets and relatives appear and disappear or change sex (or even names; in one book Snap, the dog, all of a sudden becomes "Splash."). Characters change drastically in personality and lifestyle. The fact that time passes in the books but the characters stay the same age means that aspects of prior books become impossible or highly unlikely.
- Ethnic Menial Labor: Sam and Dinah are black live-in servants to the Bobbsey family at the beginning of the series and spoke in thick accents. By the end of it, they were still black, but spoke much more clearly and it was implied that they drove in to work.
- Funetik Aksent: Sam and Dinah have very thick argot in the early books."Deed an' dat's whut she am!" exclaimed a fat, good-natured looking colored woman, smiling at the little girl. Dinah was the Bobbsey family cook. She had been with them so long that she used to say, and almost do, just what she pleased. "Dis am de forty-sixteen time I'se done bin down to de end ob de car gittin' Miss Flossie a drink ob watah. An' de train rocks so, laik a cradle, dat I done most upsot ebery time. But I'll git you annuder cup ob watah, Flossie lamb!"
- Half-Identical Twins: Both set of Bobbsey twins are explicitly mentioned to be this in the text; Nan and Bert are both tall, dark-haired and slender, while Flossy and Freddie are small, blonde and chubby.
- In-Series Nickname: Mr. Bobbsey refers to the younger pair of twins as "my fat little fireman" and "my fat little fairy."
- Not Allowed to Grow Up: Not after the first few books. Oddly enough, Nan and Bert aged four years to Freddie and Flossie's two before time froze.
- Sleep Walking: An early story involving Flossie seeing a ghost standing at the foot of her bed turns out to be Freddie sleepwalking.
- Snooping Little Kid: In some books, the Bobbsey twins will show slight traces of this trope, though surprisingly for a Stratemeyer Syndicate series, it's most often averted — nine times out of ten, the kids dump into mysteries completely by chance and even then they seldom go out of their way to investigate. Unless they suspect the culprit is Danny Rugg.
- Theme Twin Naming: Averted with Bert and Nan, played straight with Freddie and Flossie.
- Unto Us a Son and Daughter Are Born: Twice, even.