Get single selection value in CheckBoxList

i have a CheckBoxList with autopostback set to true. so when a user clicks on any one of the check boxes within, i want to get the value of that ONE checkbox clicked or unclicked. I do not want to go through all the checkboxes in the list and add the values to a string or anything. Does ANYONE know how to do this? Get just that one box that has been modified! MANY THANKS.