p1.and( p2 ).then( function( p1_result, p2_result ){...}); I believe this is equivalent to: Q.all( p1, p2 ).spread( function( p1_result, p2_result ){ ... }

p1.and( p2 ).then( function( p1_result, p2_result ){...}); I believe this is equivalent to: Q.all( p1, p2 ).spread( function( p1_result, p2_result ){ ... } ); There are other good reasons, at this point, to switch from Q to another promise lib, speed for example, as was virulently signaled recently: http://jsperf.com/wqfwewefewrw/4 http://jsperf.com/wqfwewefewrw/4