Although workers and scholars concerned with the evolution of child welfare services have general hunches about the forces influencing the directions of service development, they have not had available to them any systematic data to verify or correct their impressions. This article attempts to provide a basis for making judgments about the recent history of such services, potentially serving to indicate future directions and problems. The data presented here are intended to provide an overview of trends in Canadian child welfare services during the last 20 years. Based on recently collected material published in detail in the report entitled "Foster Care and Adoption: A Baseline Study of Canadian Child Welfare Services 1959-77," the present material offers a summary of the relationship between demographic changes in the population of children between 1959 and 1977 and the evolution of child welfare services and governmental policies in response to those changes. Topics discussed include (1) demographic developments and child welfare services, (2) residential care, (3) foster care, (4) adoption services, (5) child welfare expenditures and resources, (6) long-term trends in the child welfare services, (7) preventive services, and (8) limitations of traditional approaches to service provision. (RH)