Roy's Adaptation Model, by Sister Callista Roy, is a conceptual nursing model that views humans as biopsychosocial adaptive systems that address environmental change through the process of adaptation (Roy & Andrews, 1999; Roy & Zhan, 2006; The adaptation process can be an adaptive (positive) or ineffective (negative) response and adaptation occurs when the person responds positively to environmental changes (Roy, 1984). self that by the environment and the adaptive level is determined by the combined effect of the focal, residual and contextual stimuli (Roy, 1984). contextual “are all other stimuli present in the situation that contribute to the effect of the focal stimulus”; and the residual stimulus “are environmental factors within or outside the human system with effects in the current situation that are unclear” (Roy & Andrews, 1999). There are two interrelated subsystems in Roy's model. The primary or control processes consist of coping mechanisms or the regulator and cognator. The regulator coping subsystem provides coping mechanisms through physiological adaptive modalities involving automatic responses across the neural, chemical, and endocrine systems (Andrews & Roy, 1991). The cognator coping subsystem provides coping mechanisms through four cognitive-emotional channels which are processing, learning, judgment, and emotion (Andrews & Roy, 1991). The secondary or effector subsystem consists of four adaptive modalities: physiological/physical needs, self-concept/group identity, role function, and interdependence (Roy & Andrews, 1999). In other words…half of the paper…n & Lange.Mitchell, J. & Bray, G. (1990). Emergency services stress: guidelines for preserving the health and careers of emergency services personnel. Englewood Cliffs, NJ: Prentice Hall.Mitchell, J., & Resnik, H. (1981). Emergency response to crisis: A guide to crisis intervention for emergency services personnel. Bowie, MD: R. J. Brady Co. Roy, C. (1984). Introduction to nursing: An adaptation model (2nd ed.). Englewood Cliffs, NJ: Prentice-Hall. Roy, C., & Andrews, H. (1999). Roy's adaptation model (2nd ed.). Upper Saddle River, NJ: Pearson Education, Inc. Roy, C., & Zhan, L. (2006). Sister Callista Roy's adaptation model and its applications. In M. E. Parker (Ed.), Nursing theories and nursing practice (pp. 268-280). Philadelphia: F.A. Davis.Toomey, A., & Alligood, M. (2006). Nursing theorists and their work (6th ed.). St. Louis, MO: Mosby Elsevier.