The ICS organization adheres to a "form follows function" philosophy. The size of the current organization and that of the next operational period is determined through the incident planning process.

Because the ICS is a modular concept, managing span of control is accomplished by organizing resources into Teams, Divisions, Groups, Branches, or Sections. When the supervisor-to-subordinate ratio exceeds manageable span of control, additional Teams, Divisions, Groups, Branches, or Sections can be established. When a supervisor is managing too few subordinates, Sections, Branches, Divisions, Groups, or Teams can be reorganized or demobilized to reach a more effective span of control.