Facebook has been busy adding more companies to the list of ad providers that it has approved to work on its platform. There are now 24 by our count since the middle of last month, in addition to the 44 companies that were previously added after Facebook introduced the list last December. New names include established online ad networks like Specific Media, as well as newer companies like social video marketing platform Sharethrough.

The latest influx to the list comes as Facebook says it is starting to enforce its rule requiring developers to only work on the platform with companies that have signed its ad provider terms.

For those not familiar with what’s going on, Facebook has for more than a year required outside advertising networks and other advertising service providers to sign an agreement saying they would not do things like re-use Facebook data outside of Facebook, beyond what the terms expressly allow. That is likely why Google, in particular, has not signed on.

The requirement that developers only work with listed providers was introduced along the list itself in December. Facebook clarified in February that developers had until the beginning of March to comply before it began enforcement against those who hadn’t (it didn’t specify what the enforcement is). For those interested, check out our chronological coverage of companies that have been added.