Let the randomized query complexity of a relation for error probability be denoted by \R ( ) . We prove that for any relation f 0 1 n and Boolean function g : 0 1 m 0 1 , \R 1 3 ( f g n ) = ( \R 4 9 ( f ) \R 1 2 − 1 n 4 ( g )) , where f g n is the relation obtained by composing f and g . We also show using an XOR lemma that \R 1 3 f g O ( log n ) n = ( log n \R 4 9 ( f ) \R 1 3 ( g )) , where g O ( log n ) is the function obtained by composing the XOR function on O ( log n ) bits and g .