Is there a way to completely disable Spaces in Yosemite? Is there a way to completely disable Spaces in Yosemite (without turning off Mission Control, Dashboard, etc.)? 

As someone who frequently switches between multiple monitors and using my Macbook on its own, I frequently run into baffling setups where windows on one monitor become a Space on another monitor. I'd like to end this behavior.
I did this recently to get an iMac to better support an X-Arcade Tankstick and MAME. I do not know that it totally disabled Spaces, but is has effectively eliminated them for me.

System Preferences &gt; Mission Control: Uncheck everything.
Set shortcut for Mission Control to &quot;-&quot;

System Preferences &gt; Keyboard &gt; Shortcuts &gt; Mission control: Uncheck everything

In a Terminal window enter:
 defaults write com.apple.dock mcx-expose-disabled -bool true&quot;



For more info you can check out:

Managed Client: How to disable Exposé and Spaces

Mac OS X: Disable Mission Control and Spaces