It: book and movie differences
Stephen King's It and the films made from it differ first in shape and only afterwards in incident. The 1986 novel braids 2 timelines together chapter by chapter, the children of 1958 and the same people as adults in 1985, so that memory and event sit on the same page. The 1990 ABC miniseries kept the braid and lost the novel's content to broadcast standards. Andy Muschietti's 2017 film cut the adult timeline out completely and released it 2 years later as a separate feature. Almost every other difference follows from that single structural decision.
It: the book and movie differences, in short
The book and movie differences in It begin with a decision about time. The book is Stephen King's novel of 1986, more than 1,100 pages, which alternates between the Losers' Club as children and the same 7 people as adults 27 years later. The screen versions are 2, counted as productions rather than as instalments: Tommy Lee Wallace's miniseries for ABC, broadcast over 2 nights in 1990, and Andy Muschietti's pair of features, It in 2017 and It Chapter Two in 2019, which were developed as one adaptation and released in halves. The miniseries keeps the alternation and cannot show most of what the novel contains. The features can show it and separate the timelines into 2 releases. The central difference is that the novel makes you hold both ages at once, and the Muschietti films make you watch them one after the other.
What the novel does by keeping both timelines on one page
Keeping both timelines on one page is the novel's whole method. A chapter of the Losers' Club as children in Derry is followed by a chapter of the same character 27 years later, so the reader always knows what the child will become and what the adult has forgotten. King runs more than 1,100 pages on that rhythm, and the rhythm carries the argument: the book is about the way a place metabolises its own violence and the way adults survive by not remembering.
A third strand holds the other 2 apart. Mike Hanlon, the only member of the group who never leaves Derry, works as the town librarian and writes interludes on its history, and those interludes catalogue a century of disasters, disappearances and racist violence that the town has absorbed without comment. The entity that appears as Pennywise the Dancing Clown is not the source of Derry's cruelty in the novel. It is the beneficiary of it.
What each screen version does with the braid
Each screen version keeps or cuts the braid, and that choice defines it. The 1990 miniseries, directed by Tommy Lee Wallace and broadcast over 2 nights on ABC, keeps the alternating structure almost intact, with Tim Curry as Pennywise and Richard Thomas, John Ritter and Annette O'Toole among the adults. What it cannot keep is the content, because a 1990 American network audience sets hard limits on what a story about seven abused and terrorised children is allowed to show. Its final creature, realised with the effects a television budget of that year could buy, remains the version's most criticised passage.
Alternating chapters put the child and the adult in the same reading hour, so forgetting is dramatised on the page rather than reported.
The 2017 feature runs 135 minutes of childhood alone; It Chapter Two, in 2019, runs 169 minutes and has to rebuild the childhood in flashback to get it back.
Muschietti's pair moves the children's story from 1958 to 1989, which preserves the novel's 27-year gap and lets the adults meet in the present. It also buys the 2017 film something the miniseries never had: an uninterrupted coming-of-age story with a monster in it, which is why that film reached a far wider audience than a King adaptation usually does. The bill arrives in 2019, when the adults have to be introduced, characterised and given a childhood in flashback inside the same running time as their confrontation.
The change that mattered most: a cosmology becomes a psychology
The cosmology is the thing both screen versions had to lose. King's novel places the entity in a wider frame, an opposing creative principle in the form of a Turtle and a space outside the universe from which both arrived, and the children defeat it through a ritual of wills called the Ritual of Chud rather than through any physical act. That material is the least filmable part of the book, and neither version attempts it straight.
The 1990 miniseries abbreviates the ritual almost to a gesture. It Chapter Two keeps the name, rebuilds the ritual as a quest in which each of the 6 returning Losers retrieves a personal token from their childhood, then has that ritual fail and lets them finish the entity by belittling it until it is small enough to kill. The Turtle survives on screen as scenery. The exchange is coherent and it is a substitution: a cosmic conflict about belief becomes a therapeutic conflict about shame.
Mike Hanlon absorbs the second-largest change. The novel's Mike is the archivist who remembers on everyone else's behalf; the 2019 film makes him the one who has withheld what he knows and who drives the others into the ritual, which converts a passive keeper of memory into an active agent with a secret. Stan Uris takes his own life after the summons in both the novel and the 2019 film, handled soberly in each.
How faithful are the It films to King's novel?
The It films are faithful on character and unfaithful on voice, and no single answer covers both. Split the question by axis and it resolves. On plot the 2017 and 2019 pair keeps most of the novel's incident and rearranges when you receive it, which is a moderate distance. On character it is the closer of the 2 screen versions, because the 7 children are given the room the miniseries never had, with Mike Hanlon the one substantial reassignment. On voice it is furthest: King's shifting third person and Mike's written interludes have no screen equivalent, and Derry's documented century of violence survives as montage. On theme it lands in between, since a story about what a town does to itself becomes a story about what a childhood does to a person. A viewer who wants the incident is well served. A reader who wants the town is not.
Where the 2017 and 2019 films land on plot, character, voice and theme
The 2017 and 2019 films land far from the novel on voice and theme, close to it on character, and in the middle on plot. The bar measures the Muschietti pair; the 1990 miniseries would sit closer on voice and further on plot.
| Axis | The novel | The 2017 and 2019 films | Distance |
|---|---|---|---|
| Plot | Two timelines interleaved across 1,100 pages | Two features in sequence, childhood then return | |
| Character | Seven children, seven adults, one town historian | The same seven, with Mike reassigned as instigator | |
| Voice | Shifting third person plus Mike's written interludes | No narrator, no interludes, Derry's history reduced to montage | |
| Theme | A town that feeds on its own violence, and the cost of forgetting | Childhood trauma confronted and named in adulthood |
The answer flips for one kind of reader. Anyone who came to the novel for the children of 1958 will find the 2017 film the most faithful long-form King adaptation yet made, because that film has the room the miniseries never had and no adult plot to service. Anyone who came for Derry itself, for the interludes and the machinery behind the clown, will find both versions have kept the monster and sold the town.