Google is changing its search rankings again. And you’re going to want to have a handle on this one.

This time, it’s all about mobile. Google has been hinting for years that they prefer Responsive Design and mobile-friendly design practices more generally. But they’ve also been assuring folks that they wouldn’t be bringing down the hammer on non-mobile friendly sites — presumably by penalizing them in search rankings — any time soon.

Well, that didn’t last long. It’s tough love time.

Starting April 21, we will be expanding our use of mobile-friendliness as a ranking signal. This change will affect mobile searches in all languages worldwide and will have a significant impact in our search results. Consequently, users will find it easier to get relevant, high quality search results that are optimized for their devices.

This is, to be clear, a good thing for all concerned. Users want to land on a mobile-friendly page when they’re surfing the web — and there’s no debating the increasing percentage of traffic that comes from mobile users. If you’re a business (or creative agency) and you’re not already seriously digging into these issues … it’s time to get cracking.

From Marketpath:

The message is clear, if your current website isn’t mobile friendly (Google prefers Responsive websites), it will start to drop in Google’s mobile search results. So pay attention to your search engine results pages (SERPs) and your site volume, and more importantly, put together a plan to upgrade your website to a responsive site.

Not sure where you’re current site stacks up? Test it out for yourself here.

And if you’re not making the cut, consider this your wake up call.

More coverage here, here, and here.