Networks have launched co-viewing apps for PCs, tablets, and smartphone devices and are seeing some great results — from driving tune-in to additional engagement, loyalty, and recall. Interactive marketers looking to sync with their organizations' planned TV media buys should test new opportunities on the "second screen" to benefit from these same outcomes. Marketers can work with networks directly or with a new crop of vendors that specialize in branded co-viewing, sponsorships on check-in apps, and synchronized advertising. Second screen interactive marketing allows brands to reach new audiences and engage deeply with existing ones. To gain momentum from early tests, marketers must use new data tools to make informed media buys and pitch creative ideas to networks.