Sitemap not indexing pages

[theLotter]

My website has about 5000 pages submitted in the sitemap but only 900 being indexed.  When I checked Google Webmaster Tools about a week ago 4500 pages were being indexed.

Any suggestions about what happened or how to fix it?

Thanks!

[marcinlejman]

Hi Sara,

it's difficult to provide any specific hints without seeing the website in question.

I would suggest that you start by reading Webmaster Guidelines from Google:

http://support.google.com/webmasters/bin/answer.py?hl=en&answer=35769

Make sure that you site complies with these recommendations, especially when it comes to content. If many pages on your site are thin on content, or have duplicate content issues, these would be the likely reasons.