In this modern age of entertainment, one screen is no longer enough to satisfy most. We forecast 180.8 million US adults will be two-screen viewers in 2019—meaning that 70.1% of the adult population will use a computer or mobile device to browse online while watching either digital video or traditional TV.

And even the most compelling film and TV content can’t grab the full attention of nearly half of US adults, according to a March 2019 report from CivicScience.

Forty-eight percent of adults in the US engage with a second screen (smartphone, tablet or laptop) while watching their favorite shows and movies on TV, compared with 38% who do not. The remaining 13% either don’t watch TV, don’t own a smartphone, tablet or laptop, or they watch video only on mobile devices.

The increasing simultaneous users of internet and TV—an audience that we estimate has grown by 32.3 million in the past five years—could be an opportunity for marketers to reach subscription video-on-demand (VOD) users who don’t see ads while watching video. (CivicScience found that Netflix and Amazon Prime Video users are actually more likely to use a second screen than nonsubscribers.)

But finding out where to target this audience on their second screens won’t be easy, as the majority of viewers don’t engage in content related to what they are watching on TV. Of the 48% who browse online while watching their favorite content, 23% view mobile apps, games or other content that isn’t related to what they are watching on their main screen. Eighteen percent either text or check email, and only 7% said they view or engage with content related to the program they’re watching.

So, are second screens an opportunity for marketers, or are they just a distraction from the advertisements playing on TV? That question remains.