Yes. You can restrict access to certain sections (if your course includes multiple sections) or to groups you have created using the Groups Tool.
Instructions for restricting access to discussions, news postings, checklists, content modules, etc., are included in the Online Help for each of these components.
For instructions on creating groups, see the Online Help section Groups.
Note: In earlier versions of ICON, the management of groups was handled in the classlist. Now, there is a dedicated tool for creating and managing groups.