it is a cause of/for concern.

You should use for.

He reassured us that there was no cause for concern.

Aspara GusYou should use for.

There are 479 COCA citations for 'cause for concern' and only 35 for 'cause of concern' .It is clear that 'for' is the preposition most native speakers use. 'For' is safe, but I would not go so far as to say, "You should use 'for'"

fivejedjonThere are 479 COCA citations for 'cause for concern' and only 35 for 'cause of concern' .It is clear that 'for' is the preposition most native speakers use. 'For' is safe, but I would not go so far as to say, "You should use 'for'"

The definition for this use of cause is a reason for an action or condition, and the only appropria

Aspara GusThe definition for this use of cause is a reason for an action or condition, and the only appropriate preposition that I can think of is for. Would you say a reason of?

We cannot argue for a particular preposition after 'cause' because we happen to use it after 'reason'.

fivejedjon Aspara GusYou should use for.There are 479 COCA citations for 'cause for concern' and only 35 for 'cause of concern' .It is clear that 'for' is the preposition most native speakers use. 'For' is safe, but I would not go so far as to say, "You should use 'for'"

I would.

enoon fivejedjon Aspara GusYou should use for.There are 479 COCA citations for 'cause for concern' and only 35 for 'cause of concern' .It is clear that 'for' is the preposition most native speakers use. 'For' is safe, but I would not go so far as to say, "You should use 'for'"I would.

Fine.

I just happen to be one of those people who do not use the wo

fivejedjonFine.I just happen to be one of those people who do not use the word 'should' when I am simply expressing an opinion.

Your reserve is to be admired. I, on the other hand, am one of those people who come down hard on one side or the other once they've decided. I will, however, in homage to your tact, modify my statement and say that I can think of no

enoon I can think of no context in which "cause of concern" is anything other than a mistake.

I can live with that.

Interesting discussion.

I would have thought "cause of concern" had to do with a concern that already existed

The persistence of the drought was a cause of concern for the farmers.
(The reason that the farmers were concerned was the drought.)

and that "cause for concern" had to do with a concern that did not necessarily exist yet, but was being urged upon peop

CalifJimInteresting discussion.

Yes. This is the deep usage gris-gris.

I make that "The persistence of the drought was cause for concern for the farmers."