HOW TO: Create a Group Tumblr Blog

Tumblr blogs are known for being easy to use and simple to set up. But the blogging platform lives up to its reputation only as far as standard accounts go.

Want to set up a company blog that contributors can post to from multiple accounts? Want to use a password-protected Tumblr internally? Get ready for some help-section browsing.
Because Tumblr wants everybody’s “primary blog” to represent them, it does not allow users to create group blogs or password-protected accounts. In order to do so, you’ll need to create an additional blog under your account and then invite other members to join it. Here’s a step-by-step tutorial to get you started:

1. Create an Additional Blog

Next to the title of your blog in the right panel of the Tumblr dashboard, there’s an arrow that opens a drop down menu. In that menu there’s an option to create a new blog. Click it.

2. Name Your Blog & Set a Password

    After you click the “create new blog” tab, you’ll be asked to enter a title and domain name for your new blog. You also have the option to protect the blog with a password. If you decide to do so, only people who enter the password will be able to view your new blog.

3. Invite Members

In the dashboard of your new blog, select “members” from the menu on the right panel. You can invite members to post on the blog via email or by copying and pasting an invite link. Invited members will be able to add content to the new blog, but they won’t be able to change settings unless you promote them to be blog admins.

Important Questions

• Can I add other contributors to my primary blog? Unfortunately, there’s no way to simply add other users to a blog that you have already started as your primary blog. There’s also no way to change which blog is your primary blog or transfer that content to another blog. Which means that if you want co-bloggers, you’ll need to either share the login information for your primary blog or create an additional group blog from scratch, as outlined above. Keep in mind that you need a primary Tumblr before you can start a group one.
• Can my group blog follow or like other Tumblr blogs? Only primary blogs can follow and like other blogs. Since group blogs can’t be primary blogs, they cannot follow or like other people’s content.
• Can other people follow or like my group blog? Yes.
• Can I password protect my primary blog? Only additional blogs can be password protected.
• Is there another platform that makes it easier to create a group blog? Depending on your needs and who you ask, Posterous, WordPress and Blogger are all excellent alternative platforms for collaborative blogs.

Source: http://mashable.com/2011/05/01/group-tumblr/