That too if you’re in Apple Developer Program and have a Mac App Store access can download OS X 10.11 El Capitan. Released as beta 5, just a week after beta 4 was seeded to developers.
Developers who already in previous version of OS X El Capitan beta installed on your Mac, simply update to the latest beta 5 release directly from Mac App Store. For those first time installing OS X El Capitan on their machine from scratch, will need to download and install it from the Member Center on Apple Develop Program website.
Unfortunately, we do not have a detailed step-by-step guide on how to install El Capitan alongside Yosemite on a seperate partition on your Mac. El Capitan introduces a new system-wide font, a revamped Mission Control feature, a split-view feature for using two full-screen apps at once, deeper functionality for Spotlight, and improvements to Safari that include Pinned Sites and a universal mute button.
Apple has unveiled OS X El Capitan at WWDC 2015 keynote in June. The first beta was released to developers right after the event while a public beta program was seeded for non-developers earlier this month.
OS X El Capitan is the successor to the OS X 10.10 Yosemite. The final version of El Capitan is scheduled to release this fall. Currently available to both registered developers and public beta testers.