Is 'on' still a preposition in the phrase 'on accident', or 'on purpose'? I have noticed Americans say 'on accident', where I would say 'by accident'.

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    @JohnLawler Do Americans really say I did it on accident? If so, I've never heard it.
    – WS2
    Oct 12, 2015 at 21:21
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    I've never heard "on accident" by Americans (being one myself). We say "by accident" such as "I knocked over the lamp by accident". Could it be a regional thing? Oct 12, 2015 at 21:21
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    @KristinaLopez - I think it is some kind of wordplay judging by this for example: You're Not Here on Accident. You're Here on Assignment! books.google.co.uk/… Oct 12, 2015 at 21:23
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    I've heard "on accident" quite a bit in upstate New York.
    – DyingIsFun
    Oct 12, 2015 at 21:34
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    In my experience, "by accident" is a lot more common than "on accident" in U.S. usage—but "accidentally" may be even more common than "by accident."
    – Sven Yargs
    Oct 12, 2015 at 21:35

3 Answers 3


Is on still a preposition in the phrase on accident, or on purpose? I have noticed Americans say on accident, where I would say by accident.

Yes, it is still a preposition. It's just the wrong preposition!

I can find one example in print, i.e.

You're Not Here on Accident. You're Here on Assignment!

However that seems to be a form of wordplay. Where have you seen or heard the phrase 'on accident' being used. Did you hear it in everyday conversation? In what kind of sentence?

  • Definitely correct on the preposition front. I don't know that on is wrong so much as different usage.
    – reabow
    Oct 12, 2015 at 21:34
  • @reabow: I think given the fact that happened on accident is so rare by comparison with happened by accident, it's not unreasonable to say the former is quite simply "wrong" if it's not part of a deliberate wordplay. Oct 13, 2015 at 18:14
  • I think the premise is that if a group of native English speakers use a phrase, it is correct. This is even if it differs from standard English. I think you will find it widespread enough to meet this criteria.
    – reabow
    Oct 14, 2015 at 4:14
  • @reabow - This is a perennial problem on this and other English language sites. There are two main schools of thought. Some of us believe that there is such a thing as 'correct' English and that it is to be found in dictionaries and grammar books. Others of our number think that correctness is determined by a sufficient population of speakers even if their speech does not conform to said reference books -- or any reference books at all. If you think it is widespread then that is fair enough. I think you need some evidence of that spread though. So far I haven't seen enough to convince me. Oct 14, 2015 at 8:10
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    @FumbleFingers, I don't see there an answer to the question I asked you. Unless you mean that "quite simply wrong" means "is seldom written in books". Is that what you mean? Or "is locally standard"? ("On accident" sounds fine, to me, though I wouldn't use it in a formal setting. I consider my speech to be standard.)
    – Greg Lee
    Oct 15, 2015 at 12:56

I see in various comments people saying confidently that "on" is a preposition in "on accident" and "on purpose", but I don't see anyone giving evidence that this is actually true. How can you tell? Maybe it's a prefix, fulfilling a function similar to that of "-ally" in "accidentally" (which, after all, means "on accident").

The "accident" inside "accidentally" can't be preceded by an article or modified by an adjective, *"the-complete-accident ally", naturally, because you can't go inside a word and modify part of it, or put an article with part of it. So lets test "on accident": *"on the accident", *"on complete accident" are not acceptable. The "accident" inside "on accident" is not behaving as we would expect it to, if it were an independent word. That is evidence that "on accident" is not two independent words, even though it is written with an internal space in English orthography.

Notice that "by accident" is different, since "by complete accident" is fine, and similarly "by an accident of circumstances".

I will be looking forward to seeing some evidence from those of you who thought it was so obvious that the "on" in "on accident" and "on purpose" was a preposition.

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    Uh, "on accident" isn't a standard American English expression (as the comments above strongly indicate). So your above arguments are just jaw flapping.
    – Hot Licks
    Oct 12, 2015 at 22:57
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    @HotLicks, your comment is not relevant to the question or my answer.
    – Greg Lee
    Oct 12, 2015 at 23:48
  • Greg, the fact (if it be such) that ' on accident' is not actually a phrase in normal English is relevant to the question, and does invalidate your answer. Oct 13, 2015 at 18:01
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    @TimLymington, please explain to us how the fact that "on accident" does not occur in some standard dialects tells us whether "on" in the expression is a preposition. If you review the question, you will notice that it does not ask whether the expressions are standard.
    – Greg Lee
    Oct 13, 2015 at 18:09
  • @GregLee - do you consider 'on demand' a similar case, bearing in mind that there's no "demandly" equivalent to "accidentally" and "purposely".
    – JHCL
    Oct 13, 2015 at 22:03

My kids say "on accident" all the time. It drove me crazy at first, until I heard many of their friends using the same terminology.

A recent study by a bona fide linguist concludes that this is indeed generational:

A high-school English teacher asks which is correct: It happened on accident, or It happened by accident? A survey by linguist Leslie Barratt at Indiana State University indicates that most people born after 1990 use on accident, and weren’t even aware that by accident was proper, while those born before 1970 almost always say by accident.

You can hear the podcast at this website.

Another grammar site addressed this issue more than a decade ago, back in 1999:

I don't know where "on accident" comes from. My kids used to use this phrase all the time. "It's not my fault. It happened 'on accident'!" I thought it was a regional expression, something they picked up in southern New England, but it crops up all over. "By accident" is certainly the more common, standard expression. The preposition "on" seems to have imperialist tendencies, creeping into places — "standing on line, waiting on the bus" — where "in" and "for" were doing their job quite nicely.

This seems to be a case where the Ngram isn't going to support the younger generation, but, like it or hate it, the language appears to be evolving anyway – perhaps on accident.

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