Thank you so much for your reply. The first one printed out some results but I don't seem to be getting it to group the ID's together. Maybe I did something wrong when I was importing the different code?? I'm not sure. I so much appreciate your looking at this for me. This is the code I just tried to use:

#!/usr/bin/perl -w

open (IN, "c:/work/Abnova_Grouping/Abnova_App_and_Key.txt");
open(OUT, ">c:/work/Abnova_Grouping/Abnova_App_and_Key_Sorted.txt");

     my%AB;
while(<IN>){ 
     chomp;
         my($id, $prod_num, $app, $note)=split /\s^,\s^/;
     $AB{$id}{app} .= ",$app";
     $AB{$id}{prod_num}="$prod_num, $note";
    
}

for (keys %AB) { $AB{$_}{app}=~s/^,//}

for my $id (sort keys %AB){
    print OUT "$id, $AB{$id}{prod_num}, $AB{$id}{app} \n";
    }
    
close IN;
close OUT;
[download]

Thank you again for your help!!