The act of turning a basic group into a dynamic group removes all existing members from the group, so we recommend creating a brand-new group (with no members), rather than re-using an existing group. As part of the process of converting a group into a dynamic group, you must create at least one membership rule for the group.

1. Navigate to an OU where you have privileges to create groups.
2. Right-click the OU and select New then select Group.
3. Name your new group, then click through the group creation screens without adding any members to the group.
4. Right-click on the group, then select Convert to Dynamic Group. You'll be warned that converting to a dynamic group will remove all its members. That's why we told you not to add members in the previous step.
5. Click Yes. A New Membership Rule Wizard will open.

You then create your first rule defining group membership.