Moose did (and perhaps still does) have issues with threads (see this RT bug), but it coredumped and was related to the regexpr that we used to parse the types. It is quite possible Moose has other issues with threads and no one else has encountered them yet. I personally never use Perl threads and I know very few people who do as they are notoriously broken/buggy/problematic. You might want to give Net::Twitter::Lite a try, it is a non-Moose version of Net::Twitter so would at least remove the Moose component from the issue (since I am pretty sure from your code you don't really care about the Moose-ness and are only interested in making this work).