How do affiliate links affect your search ranking?

How do affiliate links affect your search ranking? The simple answer is, not at all.

Most affiliate programs are managed by a third party e.g. Commission Junction. Whether you link out to these programs as an affiliate, or have inbound links as a merchant, the affiliate network acts as a filter for passing any value in the link.

If you've joined an affiliate network as a merchant then your objective should not be to improve your own site's rankings. If it is, then your strategy will not work. Your objective should be to help your affiliates improve their own sites in the search engines by providing them with advice, tools and content. Your affiliate's success is your success.

If you're worried that your outbound links to affiliate programs will affect your site negatively in the search engines, there is no evidence to support this. Google don't care what affiliate programs you link to, only that your site adds value to the sales process by providing unique, useful and relevant content. If you're promoting an affiliate product your job is not to sell. That's the merchant's job. Your job is to pre-sell. In other words, send your visitor to the merchant's site in the right frame of mind - informed and ready to buy.

Linking for SEO and affiliate marketing are two different endeavours. To do well in the search engines you need to have a linking strategy, but affiliate programs shouldn't be part of that strategy.