I regularly use the return values of deferreds to simulate synchronous behaviour like this: def handle_db_result(result): if ({some logic stuff}): return True else: return False def check_db(): d = {some db query that returns a deferred} d.addCallback(handle_db_result) return d def main_func(): if check_db(): # This eventually returns True or False # Do some stuff else: # Do some different stuff So now I'm trying to do the same thing with DeferredList's, but apparently the semantics aren't the same. Here's some actual runnable sample code trying to use the DeferredList: from twisted.internet import reactor, defer def callback_function(results): return "(--> This is the value that I want to get into retval! <--)" def make_a_list(): deferred1 = defer.Deferred() deferred2 = defer.Deferred() dl = defer.DeferredList([deferred1, deferred2]) dl.addCallback(callback_function) deferred1.callback('one') deferred2.callback('two') return dl # The crucial line! def test(): retval = make_a_list() print "retval is:", retval reactor.callWhenRunning(test) reactor.callLater(2.0, reactor.stop) reactor.run() The actual output of the above script is: retval is: <DeferredList at 0x7a30a8 current result: '(--> This is the value that I want to get into retval! <--)'> Through some trial and error I found that if I change that "crucial line" above to "return dl.result", then it appears to work how I like. Is that what I should be doing, or did I just get lucky in that particular instance?? Also, I notice that if one of the deferred's errbacked, then the DeferredList seems to errback as well. It shouldn't do that according to http://twistedmatrix.com/projects/core/documentation/howto/defer.html#auto7 ... so I filed a bug (#3323). ~ Nathan