Annual crop production in the Canadian prairies is undergoing significant change. Traditional monoculture cereal cropping systems, which rely on frequent summer‐fallowing and use of mechanical tillage, are being replaced by extended and diversified crop rotations together with the use of conservation tillage (minimum and zero‐tillage) practices. This paper reviews the findings of western Canadian empirical studies that have examined the economic forces behind these land use and soil tillage changes. The evidence suggests that including oilseed and pulse crops in the rotation with cereal grains contributes to higher and more stable net farm income in most soil–climatic regions, despite a requirement for increased expenditures on purchased inputs. In the very dry Brown soil zone and drier regions of the Dark Brown soil zone where the production risk with stubble cropping is high, the elimination of summer fallow from the cropping system may not be economically feasible under present and near‐future economic conditions. The use of conservation tillage practices in the management of mixed cropping systems is highly profitable in the more moist Black and Gray soil zones (compared with conventional mechanical tillage methods) because of significant yield advantages and substantial resource savings that can be obtained by substituting herbicides for the large amount of tillage that is normally used. However, in the Brown soil zone and parts of the Dark Brown soil zone, the short‐term economic benefits of using conservation tillage practices are more marginal and often less profitable than comparable conventional tillage practices.

An intensive case management intervention for homeless persons was evaluated by random assignment of 202 cases (involving 213 adults and 70 children) to the intervention or a control group. Full follow-up data (4 interviews: at baseline and at 6-, 12-, and 18-month follow-ups) were available on 98 cases (105 adults and 37 children). The follow-up rates for the 2 groups were not significantly different. Based on 13 repeated measures analyses, there were 3 statistically significant linear time effects (indicating overall change across the follow-up period) and 3 linear Time x Condition interactions (indicating differential change over time for intervention vs. control participants). Regardless of condition, adult participants improved in terms of their experience of homelessness, as well as on physical health symptoms and stressful life events. Condition x Time interactions indicating positive intervention impact were observed on the quality of housing environments, stressful life events, and interviewer ratings of psychopathology.

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To separate the characteristics of the homeless from those of the housed poor, 144 adults were randomly sampled from several sites, yielding 3 groups: the currently homeless (n = 59), the previously (but not currently) homeless (n = 31), and the never-homeless poor (n = 54). The homeless were significantly less likely to be receiving public benefits, were more likely to have a DSM-III (Diagnostic and Statistical Manual of Mental Disorders [3rd ed.; American Psychiatric Association, 1980]) diagnosis of substance abuse, showed higher levels of self-rated psychological distress and were more likely to be victims of recent domestic violence and to have been physically abused as children. The homeless did not differ from the comparison groups on DSM-III diagnosis of severe mental illness (schizophrenia or major affective disorder). physical health symptoms, and social support and social networks.

This article presents an ecological perspective on homelessness that emphasizes the context in which homeless people live and the complex interactions between personal, social, economic, and service system resources that affect their well-being. The ecological perspective encourages researchers and program developers to assess the problems of homelessness at multiple levels of analysis, to view homelessness as a result of contextual factors that interact with individual and family vulnerabilities, and to assess carefully the social contexts in which researchers and program developers operate. Four ecological principles are described as a heuristic for research, intervention, and policy development. The implications of an ecological perspective for psychologists who wish to get involved in dealing with homelessness are discussed.