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The best way to think about this is - what happens if you don't do the 301 redirect from the old pages? Any links to those pages will be worthless (as the spiders will end up at a 404 error page, so the search engine will eventually drop the page from the search results) Any traffic which comes into those pages will get the same 404 page - so any referral traffic which follows those links in will be lost You're forcing the spiders to start from scratch again with your site - to spider and index all the content from the home page What approach you take depends on your timescales, and how quickly you're going to create the new content.  I'm also assuming that maintaining the existing URLs either isn't feasible or there's more value in creating new URLs (e.g. old ones were www.domain.com/index.php?id=3483844 and ones are www.domain.com/category/title-title-title.) I would be tempted to try and do both at once - just doing the redirect will get people going to the correct URL, but the content will still be regarded as "old" by the search engines.  Substantially changed content going onto new URLs will get the benefit of the 301 from the old URL (for referral links etc.), plus a "look again" from the spiders as it will be considered 'fresh'. There is a very good recent discussion from a couple of weeks ago about new vs. old content http://www.seomoz.org/blog/new-links-old-pages-whiteboard-friday and one from November at http://justinbriggs.org/methods-for-evaluating-freshness