This white paper analyzes factors that correlate with high search engine rankings based on data from 2013. On-page factors like keywords, page load times, and rich content remain important but keywords in domains and URLs have decreased in relevance. Backlinks are still very influential; natural, diverse links from sites with high SEO visibility are most valuable. Social signals continue to correlate strongly with rankings. Google+ emerged as highly correlated, suggesting it may overtake Facebook in importance by 2016. Top ranks are difficult without a strong brand factor. Wikipedia results influence correlations and occupy specific ranks.