Abstract Explores 3 possible reasons for the failure of the link between theory and assessment in family psychology. A primary reason for the failure is a lack of a multilevel unified theory of family functioning. A 2nd reason is that, in addition to multiple, uncoordinated theories, many family constructs are not yet refined enough for behavioral definitions. A 3rd problem in the connection of family theory to family assessment is the lack of attention to the measurement of change in family variables.