Creating subcategories within portfolio?

Site URL: http://evanwilsonstudio.com

Right now my site structure looks like this:

Work

• Project 1
• Project 2
• Project 3
• Project 4

I would like it to look like this:

Work 

• Category A
  • Project 1
• Category B
  • Project 2
  • Project 3
• Category C
  • Project 4

Is there a way to create this kind of structure?

Using 7.1

Thank you!

I'm looking to achieve something like this as well. Is there no way to have category  / sort options within a portfolio page? Or drop several portfolios into a single page? This needs to be addressed. I have a portfolio website for my graphic design agency and would like to be able to sort on one portfolio page or page by web design, branding, print, etc... Please help. This functionality has to be available, yes? If not, why?

Hi. You can try Universal Filter Plugin.