This document provides information on two nursing theorists: Sister Callista Roy and Dorothy Johnson. It summarizes Roy's Adaptation Model, which views the person as an adaptive system interacting with the environment. The goal of nursing within this model is to promote adaptation. It also summarizes Dorothy Johnson's Behavioral Systems Model, which views the person as a system of organized subsystems that work to maintain stability. Johnson identified 7 subsystems that help the person maintain a steady state through adjusting to internal and external forces.