You have to import the module first to be able to access its subs: use AnotherMod qw/parameters/; and then you can get your sub reference either with the package name like Thread->new(\&AnotherMod::subName, @args); or without like Thread->new(\&subName, @args); depending on whether your module exported those subs into your caller's namespace or not.

Edit: I still should think twice about what I wrote, you use a module, not import