Effective altruism may be the fastest growing charitable movement you've never heard of. With 1.2 million views and counting for Peter Singer's TED Talk on the subject, and Givewell, the flagship charity evaluator of the movement, now moving more money than Charity Navigator, it's worth getting to know the basic tenets of Effective Altruism before making your next donation. Tee Barnett, the Programs and Educational Officer at Charity Science, will explore the potent blend of applying "the greatest good for the greatest number" to evidence-based and rational decisions about charity. With such growth in only a few short years, key tensions have arisen that the Effective Altruism movement will have to address: how can we measure the greatest good for the greatest number? Can the movement be sustained? Is this the most compassionate way to understand charity? Should we be thinking more globally? Largely populated by humanist, skeptical, secular, rational, and atheistic types, a second look is required of this newly reframed outlook on helping those in need.