This study is an examination of the positive and persisting psychological and behavioral aftereffects in eight individuals who reported consumption of psilocybin-containing mushrooms. Mushrooms containing psilocybin have been used for healing and spiritual purposes for thousands of years, and the therapeutic applications of psilocybin were scientifically examined beginning in the mid-20th century. Research from this era suggested that psilocybin was indicated as an effective adjunct to psychotherapy for conditions such as depression, anxiety, chemical dependency, and obsessive-compulsive disorder. Recent research at the Johns Hopkins School of Medicine demonstrated that participants who consumed psilocybin reported having profoundly meaningful experiences, and that these participants experienced persisting and positive changes to their mood, attitude, and behavior at 1-month and 14-month follow up. However, there has not yet been ample research examining the mechanism of the connection between participants’ experience with psilocybin and the existence of these positive and persisting aftereffects. This study employed a phenomenological approach, using an unstructured interview to gain an understanding of participants’ description of this mechanism. Eight adults were interviewed who reported using psilocybin in the past. A within-case analysis and cross-case analysis were conducted on the data, producing 11 themes within three categories: Set (which included the themes of Preliminary Anxiety and Substantial Preparation); Experience of Psilocybin Effect (which included the themes of Profound Shift in Attention, Unity Consciousness, Increased Introspection, Positive Emotional State, and Transcendental Experience); and Persisting Aftereffects (which included the themes of Short Term Reduction in Anxiety, Persisting Insight, Assistance with Psychological Distress, and Inspired Behavioral Change). Participants maintained insights gained during their experience of psilocybin far beyond the course of the substance. This research suggests that the positive and persisting aftereffects related to the consumption of psilocybin may be useful for psychological healing and growth, and that these aftereffects should continue to be studied.