Although microfinance client numbers have roughly quadrupled in the last half-decade, they still represent the proverbial drop in the bucket of potential clients. Some 650 million Muslims hover at or below the poverty line today. There are five takeaways from CGAP's most recent research on the subject, "Understanding the Costs and Sustainability of Sharia-Compliant Microfinance Products". First, some "Islamic" products are tough to scale. Second, comparing Islamic products to conventional microfinance doesn’t always work. Third, sustainability is possible, but it will take significant investment. Fourth, we need more time to understand how these products are working - and who is using them. Fifth, in the meantime, Islamic financial service providers are here to stay.