Yes, Google will include web pages with or without accents in search engine results, but the mix will vary.

Especially Non-English speakers are faced with a problem when it comes to words with accents. Is it Mexico or México? And what happens if you search for one or the other?

Well, the short answer is that Google will include web pages containing both variations in the search engine results, regardless of which variant you put in the search form.

You may force Google to sort out one spelling only by putting a + sign in front of the word, like this: +México.

Google may still include a few pages with Mexico (caused by the fact that the anchor text of inbound links may be using the México alternative), but most of the pages will include México only).

However, in a Webmaster Radio podcast Vanessa Fox of Google adds that search engine results may vary from user to user.

The mix of search engine results is, for instance, influenced by the home page of the user (using google.es will bring up more pages with México than Mexico as compared to google.com).

Google will also take the language of the google.com home page into consideration. If you select Spanish as your preferred language, more Spanish language results will appear.

Finally, Google may also take a look at your IP number in order to determine where you are in the world. Searching google.com from Venezuela may therefore also give you different SERPs or search engine result pages.

All of this is good news for searchers, who will — in most cases — get more relevant results.

This is a nightmare for search engine marketers, however, as it makes it harder to determine the ranking of web pages in search results.

What does it mean to be No. 8 in Google for a certain term? Is it No. 8 in the US, or No. 8 for Spanish language users? Furthermore, the same keyword phrase can be No. 9 in English language results in Norway, as google.com may access a different data center in Oslo, Norway than in Baltimore, USA.

This is all part of the process towards personalized results, where Google and other search engines take the personal interests or social or cultural context of searches into consideration. And indeed, if a Google searcher has personalized search enabled — a feature that takes what you’ve searched for in the past into consideration– that will also influence the search results.

See also: Official Google Webmaster Central Blog