Normality and exceptional values of derivatives

We show that a family F of functions meromorphic in some domain is normal, if for all f is an element of F the derivative f' omits the value 1 and if the values that f' can take at the zeros of f satisfy certain restrictions. As an application we obtain a new proof of a theorem of Langley which clas sifies the functions f meromorphic in the plane such that f and f " have no zeros.