This paper is concerned with synchronization of distributed node dynamics to a prescribed target or control node dynamics A design method is presented for adaptive synchronization controllers for distributed systems having non-identical unknown nonlinear dynamics and for a target dynamics to be tracked that is also nonlinear and unknown The development is for strongly connected digraph communication structures A Lyapunov technique is presented for designing a robust adaptive synchronization control protocol The proper selection of the Lyapunov function is the key to ensuring that the resulting control laws thus found are implementable in a distributed fashion Lyapunov functions are defined in terms of a local neighborhood tracking synchronization error and the Frobenius norm The resulting protocol consists of a linear protocol and a nonlinear control term with adaptive update law at each node Singular value analysis is used It is shown that the singular values of certain key matrices are intimately related to structural properties of the graph (C) 2010 Elsevier Ltd All rights reserved