Based on the examples in the Drools Expert documentation, I have a rule like this (simplified version here): when Search($t : town) $results : ArrayList() from collect ( Person (town == $t) ) # $p: Person(town == $t) # this works then System.out.println("Matches for " + $t); System.out.println($results.size()); # this produces 0! # System.out.println($p.getName()); # this works end When I use instead the commented out lines in the "when" and "then", it prints out a list of names of matching people. However when I tried to collect the matching people into an ArrayList for use in the "then", I got nothing, so I tried to test it by printing out the size of the list as shown above, and I found that the size was 0, so it's clearly not collecting matching people into the list even though it works fine individually. Can anyone suggest what might be going wrong please? Thanks in advance for any help. Cheers. -- View this message in context: http://www.nabble.com/Why-might-%22collect-from%22-not-work--tp25167528p2... Sent from the drools - user mailing list archive at Nabble.com.