It's always bothered me that CFSelect validation only worked for multiple-select (list) boxes, and that we were left to our own devices to validate single-select (drop down) inputs. A few weeks ago I found a comment on Ben Forta's Blog that describes how to override the default validation function to properly handle single selects. The one caveat is that, since by nature a single-select input will always have one option selected, you have to have one invalid option. Generally I make it display, "Choose One:" or something like that. The value must be "" (not even a space).

To override the validation function, simply include this in your JavaScript somewhere. I put it in my global JS include so I never have to think about whether or not I'll need it on a given page.

var _CF_hasValue_old = _CF_hasValue;
_CF_hasValue=function(_b,_c,_d){
   if (_b.type == 'select-one'){
      var bSelected = false;
      for (var i=0; i<_b.options.length; i++){
         if ( _b.options[i].selected == true && _b.options[i].value != '' )
         { bSelected = true; break; }
      }
      return bSelected;
   }else{
      return _CF_hasValue_old(_b,_c,_d);
   }
}

Use it like so:

<cfselect name="StateCode" required="true" message="State is required." query="variables.states" queryposition="below" display="StateName" value="StateCode">
   <option value="">Choose One:</option>
</cfselect>

Again, I can't take credit for coding this. I found it on Ben's blog, and thought it should make its way into the various aggregators.