This paper suggests directions, based on the scientist-practitioner model, toward which counseling psychology should move in response to the dramatic increase in the number of stepfamilies in contemporary society. "Stepfamily" is defined as a household that includes a parent-child relationship that pre-dates the couple relationship, thus creating a stepparent-stepchild relationship. "Extended stepfamily network" is defined as two or more households that are linked together by blood or marriage/coupling, and includes at least one household in which there is a step relationship. A section on the reasons why counseling psychology should include the study of stepfamilies and extended stepfamily networks discusses demographic, theoretical, and clinical factors. Ways in which stepfamilies are different from first-marriage, two-parent families are summarized, and many of the common problems that stepfamilies bring to counseling are listed. The next section looks at theories related to stepfamilies. Most theoretical writings are based on a family systems perspective, and most of the writers are either sociologists or clinicans. Sociological explanations include family stress, social exchange, normative-resource, and sociobiological theories, while clinicians tend to approach the topic from a developmental, family therapy perspective. Useful but underutilized approaches include social psychological (group dynamics) and feminist theories. A section on research concludes that there is virtually no empirical clinical research on stepfamilies. A proposed response for scientist-practitioners is offered that includes making theoretical contributions, conducting intervention research, and integrating training in stepfamilies into the academic curricula. A bibliography of theoretical writings on stepfamilies, a syllabus for a three-credit course on stepfamilies in the Counseling Psychology Department, and information on how to order a bibliography on remarriage and stepfamilies are appended. (NB)