The leading power QCD collinear factorization formalism has been very successful in interpreting all 
data in high energy scattering with large enough momentum transfer.  In this talk, I will explore 
opportunities to go beyond this leading power collinear formalism in terms of TMD factorization and 
high twist collinear factorization.  I will use transverse single-spin asymmetries of cross sections 
in ep collisions as examples to discuss the predictive power of the new QCD factorization formalisms, 
and the rich information on hadron's partonic structure that we can learn from these new observables.