A while ago, I used to get phone calls from colleagues from all over the university with questions like how to write focussing, with single or double s. As a member of the English department I was expected to know these things. The questions have stopped coming, which may be due to the university-wide use of Microsoft Word which tells you whether you made a spelling error. (I switched this option off, because I often work with 18th-century documents, which consequently get marked with red squiggles all over.)
But I always vaguely assumed that there were different preferences between British and American English, and wonder whether people who rely on Word’s spelling checker are aware of this. But perhaps I’m wrong. I now get increasingly insecure as students correct me for writing things like: “Next time, try focussing on …”. Looking this usage feature up in Fowler (Burchfield’s 3rd edition, 1996), I read that the “proper” spelling is focusing (is it really?), but that “forms with –ss– are used by many printers and publishers”. So what do I do now? Do different publishers’ style sheets include spelling features like this?
Bridging the Unbridgeable 
According to the latest BBC News Style Guide, it is supposed to be focus/focused/focusing. I wonder whether there is a difference between American and British English.
Interesting: I’ll tell the copy editor of my book on the language of Jane Austen’s letters, who (as I just found) just added an to my “focused”.
This sounds like one I should investigate. Personally, I am quite happy to use either form, and am intrigued that so many people in your poll said that double ss was unacceptable in any circumstances.
Yes, so am I: I can never remember which of the two to use in any case, so always have to look it up when (as now) I’m editing a collection of papers. This btw is also a question on which our blog is consulted EVERY DAY!
Thanks, Ingrid. I also always have to double-check; clearly, many other mother-tongue speakers have to as well. I’m interested to hear that users consult your site about it every day! I’d be fascinated to know if you have information on recurring topics of this kind from visits to your site/blog: I’m already collecting amendments and corrections to my edition of Fowler for a possible next edition, which will have to cover e.g. focus in more depth. Kind regards, J.
Congratulations on your book: we were really pleased to hear about it. And: thanks for getting in touch.
The search times we find most frequently (though I have no ready data on this here) are indeed focussed/focused, kind regards/best wishes, thusly and … John Honey. I want to organise a session (workshop perhaps) on John Honey. As soon as I have a little more time …
Thanks, Ingrid! ‘Thusly”. Oh dear. Dank u wel, anyway.
I’m in favour of the double s because people who are not firm in English pronunciation woule otherwise be misled to read it with end sounding like “using” as in “accusing”. Focussing and fussing fit, you wouldn’t want to spell the latter “fusing” either.
Agree completely. This dropping of the double consonant is appearing everywhere – “traveling”, “unraveling”, and now “focusing”. English is already a difficult language with all of the exceptions to so-called ‘rules’. This only contributes to more confusion. The double consonant should ensure the short vowel pronunciation.
Ever more grammatical rules are being discarded with the argument that language should be allowed to evolve. And indeed, it should evolve, but not into SMS- or Twitter-format. There was a valid reason why focus would deflect into focussing: the “double s” helps legibility. The example of “fussing” and “fusing” may not be entirely applicable, as the first is derived from “to fuss”, the second from “to fuse”. However, pronunciation-wise the example stands. And I am afraid British publishers do not necessarily have to be right: it is not because many do it wrong that it becomes right.
when i look up focusing on google i get first “a psychotherapeutic process developed by psychotherapist Eugene Gendlin. ” when i tyoe in focussing i get “is it spelt focussing or focusing” – This answer tells me it should be focussing … or maybe not?