Conditional Format: Highlight cells in Column C that refer to Column B

maybe you can try this:

Go to conditional formatting > New Rule > Use a formula

then type this formula =AND($B1<>"",$C1=$B1)

choose the applicable format then apply to column C ($C:$C)

Do you mean you want to change the color of cells that have a formula in them that refeneces anpother cell?
If so, then sorry, CF cannot do that. All regular formulas work on what is displayed in a cell, not what the contents are - in other words, if a cell has =1+2, it will show 3, and excel will only see 3

If, on the other hand, you mean you want to change C based on what B shows, then, you will need to give additional info please

On a side note, bhenlee, you should avoid applying CF to entire columns, it will start to slow your file down