The purpose of this study was to test a causal model developed from a theoretical formulation of the health consequences of loneliness in adolescents. The sample consisted of 325 adolescents, ages 12 to 21. Data were obtained in classroom settings on the variables of age, gender, and loneliness on one testing date; and on the variables of introspectiveness, symptom patterns, and perceived health status on another testing date 1 week later. The causal model was tested via the LISREL 7 program. By all indicators used in this study, there was a very good fit of the overidentified model with the data, the causal relationships predicted in the model were correctly specified, and modification of the model was not indicated. The results indicated that loneliness contributed to introspectiveness, that both loneliness and introspectiveness contributed to the reporting of symptom patterns, and that all of the aforementioned variables contributed directly and/or indirectly to a less positive perception of health status among adolescents. A vast majority of the direct and indirect effects of age and gender predicted on other variables in the model were supported. © 1993 John Wiley & Sons, Inc.