This dissertation deals with the relationship between a person's emotional development and physical diseases. The term 'development' refers to development over the lifespan (Paper 1 and Paper 2) and to the development of competencies over training (Paper 3). Emotional development is operationalized in this dissertation via several emotional constructs: Early trauma (Paper 1), the tendency toward negative emotions and quality of emotions (Paper 2), and emotional competencies and their enhancement via training (Paper 3). Physical diseases are measured via self-report (slight deviation in Paper 1) and via the assessment of the impairment through various disease symptoms, which are comparable across all three papers (disease symptoms, Paper 1 (also objectively measured); physical complaints in adolescents, Paper 2; disease symptoms in young adults, Paper 3). Emotional processes within a person are fundamental in predicting physical disease. They are of value for future studies as well as for practice and should be further investigated and applied.:Summary 6 1 Basic Ideas About This Dissertation 10 1.1 Historical Outline: The Connection Between the Soul and the Body 10 1.2 Research Gaps and Aims of the Dissertation 13 1.3 Previous Theories and Models Explaining the Relationship Between Psyche and Diseases 16 2 Resulting Model: How Does the Emotional Development Influence Physical Diseases? 25 2.1 Resulting Model for the Underlying Dissertation 25 2.2 How Does (Early) Stress Affect the Body? 27 2.3 How Does Emotion Affect the Body? 29 2.4 How Does Emotional Competence Affect the Body? 30 2.5 Definition of Physical Diseases 32 3 The Role of (Early) Stress 38 3.1 What is Stress? 38 3.2 The Experience of Trauma in Childhood 39 3.3 Adverse Childhood Experiences and Diseases: The Need for Further Research 40 3.4 What are the Objectives of the First Paper? 40 3.5 First Part of Research Questions for the Underlying Dissertation 41 3.6 Paper 1: Adverse Childhood Experiences and Physical Diseases in Adulthood: A Summary of Meta-Analyses 42 3.7 Problems with the Trauma- and the Stress-Variable 67 4 The Role of Emotion (Paper 2) 68 4.1 What are Emotions? 68 4.2 Effects of Specific Emotions on Specific Diseases and Other Predictors in This Regard 69 4.3 What are the Objectives of the Second Paper? 70 4.4 Second Part of Research Questions for the Underlying Dissertation 71 4.5 Paper 2: Physical Health Complaints in Adolescents: Findings from the 2018 Brandenburg HBSC Study (Paper 2) 72 4.6 Difficulty in Measuring Emotions 93 5 The Role of Emotional Competence (Paper 3) 94 5.1 What are Emotional Competencies? 94 5.2 The Need for Paper 3 96 5.3 What are the Objectives of the Third Paper? 97 5.4 Third Part of Research Questions for the Underlying Dissertation 97 5.5 Paper 3: Effects of Emotional Competencies on Disease Symptoms 98 6 Conclusion 126 6.1 Comparison of the Studies 126 6.2 A Few Answers to the Opening Questions 131 6.3 Assumptions of Psychological Characteristics as Causal Factors 132 6.4 Explanation of the Connections Between the Emotion-System and the Body-System 133 7 Practical Implications 134 7.1 Relevance of the Findings for Parents and Caregiving Institutions 134 7.2 Relevance of the Findings for the Health Care System 138 7.3 Relevance of the Findings in the Light of Covid-19 141 8 Research Gaps and Outlook 142 9 References 146 Appendix 177