Windows Authentication Doesn't automatically grab user credentials
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I have an aspx site that I'm working on for our company's intranet. I recently added some secure pages that require the user to be a member of particular groups in an Active Directory in order to view. We are using Windows Authentication for the site(I have windows authentication in the .config). Windows Authentication is enabled in the IIS, and Anonymous Authentication is disabled. I've also enabled NTLM Authentication in the projects properties.

As far as I can tell, the security stuff is working as expected. Only users with the proper credentials can access the secure pages (I'm securing them with the [Authenticate Roles = "bla"] check on the controller action).

The problem I'm having is not really a problem, but more of an annoyance. Whenever the user logs in to the site, they are prompted with a login dialog. I don't want this. I want the site to grab their credentials from the windows login and use that to determine their access rights.  I was under the impression that Windows Authentication handled this on its own, but it appears I was wrong.

Basically, how can I get rid of the login prompt and have Windows Authentication handle all of that same functionality automatically?

Is there some server setting I might need to change? Could it be something in my code?

I've looked into changing the IE security settings, but I that's something I'd have to get with our System Admin on and I'd want to be sure that it would work before I tried. Plus, the IE security setting stuff seems like it would be user specific(meaning each user would have to go in and change that themselves), which isn't ideal. Additionally, I want it to work with at least IE, Firefox, and Chrome, if that is at all possible.

Sorry if I flubbed in some of my questions, but feel free to tear me down if need be. I'm a brand new software developer(just started work a couple months ago) and I'm here to learn.