In Post-War England, Jill Crewe's life isn't going well. Her father has just died, and her mother has moved to Chatton with her daughter. Pond Cottage, their new house, is nice enough, but Jill lacks one thing essential to Chatton's social scene: a horse. However, the Crewes simply don't have the money to remedy this; Catherine Crewe, Jill's mum, is a struggling children's book author, and finances have been difficult after Mr. Crewe's death. They don't even have enough for regular riding lessons. All Jill can do is look longingly at the students from the nearby riding school as they pass by Pond Cottage on their afternoon hacks.

Things start looking up, however, when Mrs. Crewe lands a book deal, Jill meets both a sweet-tempered pony and the friendly, talented Ann Derry, and ex-RAF pilot (and former rider) Martin Lowe offers to become Jill's riding instructor. Soon, Jill is winning gymkhanas, having adventures, taming unruly ponies and having face-offs with the snobby, rich Susan Pyke.

Books in the series are:
* ''Jill's Gymkhana''
* ''A Stable for Jill''
* ''Jill has Two Ponies''
* ''Jill Enjoys Her Ponies,'' a.k.a ''Jill and the Runaway''
* ''Jill's Riding Club''
* ''Rosettes for Jill''
* ''Jill and the Perfect Pony''
* ''Pony Jobs for Jill,'' a.k.a. ''Challenges for Jill''
* ''Jill's Pony Trek''

Written from 1948-1962, Ruby Ferguson's ''Jill'' series is widely acknowledged as one of the first and most influential of the PonyTale genre. As such, most of the tropes listed under that page can be found in at least one of Jill's nine-book long series.

The books have been edited and changed over time, with large sections missed out of some editions, references to make-up vanishing and currency changing (especially since shillings and crowns had changed to pounds and pennies in the interim). Most notably, the name of Jill's first pony, Black Boy, was changed to Danny Boy in the 1970s (perhaps because of concerns over racism)...only to change back in later editions. For the sake of consistency, this article will refer to Jill's first pony as his original name.

!!The ''Jill'' series provides examples of:

* AnachronicOrder: Justified in the original edition: ''Pony Jobs for Jill'' is clearly the last book in the series timeline, with Jill and Ann having left school, but ''Jill's Pony Trek'' is prefaced with an older Jill and Ann trying to remember a story that she hasn't yet told her readers, coming up with the titular pony trek. However, the Knight edition put ''Pony Jobs,'' now retitled ''Challenge for Jill,'' at number 6 in the reading order, which means that come book 7 (''Perfect Pony''), the reader has jumped back in time with no explanation.
* CoolHorse: Mrs. Darcy's Thoroughbred, Blue Smoke.
* GrowingUpSucks: ''Pony Jobs for Jill'', a.k.a ''Challenges for Jill''. Jill and Ann, accomplished riders, instructors and stable workers by this point, spend six months trying their hand at jobs which they should excel...only to get consistently screwed over by clueless and inept employers. By the end of the book, Captain Cholly-Sawcutt, until now one of their most reliable allies, sternly tells them that it's time to stop playing with their ponies (although they are free to keep them as a hobby) and take a ''real'' job. This being 1960s England, that means it's time to study to become secretaries.
** This last one is something of a double whammy, as Captain Cholly-Sawcutt previously offered Jill a job working for him when she leaves school (although no mention was made of Ann) and the reader is never told just how, when or why he changed his mind.
* InformedPoverty: The Crewes are struggling financially at the start of the series, but later on Jill still thinks of herself as relatively poor while clearly having wnough money for the upkeep of her two horses.
* InspirationallyDisadvantaged: Martin is a more believable variety of this character archetype. He's in a wheelchair, and isn't going to recover the use of his legs, but he accepts his situation, carries on as usual and is one of Jill's staunchest supporters.
* MistakenIdentity: In ''Jill and the Perfect Pony'', Amanda Applewood is supposed to be riding as part of the Lockett's equestrian team, but asks Jill to fill in for her as...well, she simply can't be bothered. However, she doesn't tell the Lockett family about the switch, and Jill is horrified to be addressed as "Amanda" when she arrives. Furious, Jill maintains the lie, and tries to be obnoxious as possible in order to give Amanda the rotten reputation than Jill feels she deserves.
* PonyTale: One of the most well-known of the genre.
* ReasonableAuthorityFigure: Most adults who are not school teachers or obnoxious mothers. Martin Lowe is friendly, although he encourages responsibility, and Mrs. Darcy is famous for her firm but fair approach.
* SilentSnarker: Jill strongly believes that certain horses are this, especially Rapide. Then again, she might just be putting words into their mouths.
* SneakersOfSneaking: In ''Jill has Two Ponies'', Jill has hunger pangs in the middle of the night. So as not to disturb her mother as she sneaks to the kitchen, she does not wear her slippers, as they are apt to go slippety-slop: instead, she goes barefoot.
* {{Tsundere}}: Jill's second pony, Rapide, is an equine version. He's awkward and unco-operative when Jill first meets him, and she buys him mainly out of a sense of pride ("no pony is going to get the better of me!"). When he warms up to her, he becomes her go-to jumping pony and can be very affectionate, but he maintains his grumpy streak as well.
* UnderdogsNeverLose: Sort-of averted; Jill is never guaranteed the first place ribbon, and several shows are a disaster for her. However, she ''is'' almost certain to do well at the most important show in the book (nearly always the one at the end).
* UnwantedAssistance: Melly and Lindo, in ''Rosettes for Jill'', have a bad case of this. Lindo's attempts to paint the stable turn everything in range a rather distressing shade of blue. After laming Jill's dependable Black Boy when they take him out without permission, ruining him for an upcoming show, they try to make up by giving her their CoolHorse, Blue Shadow, instead, but (unknown to them) Blue Shadow is ring shy, and bolts when Jill rides her in the show.