This text presents the ""state of the science"" based on King's conceptual system and Theory of Goal Attainment. Students and graduates of nursing education courses at the master's and doctoral level will find it useful in order to understand the foundational work conducted by others. Practicing nurses will also gain an appreciation as to how King's conceptual system and new middle range theories can be applied to clinical practice questions. It is also hoped that this text will encourage other nurses to begin the work of developing and testing middle range theories.