General Audience Summary Previous studies have demonstrated that the reasons why people share personal experiences with others can be related to the mental health of older adults. These studies have mostly been based on data collected from Western individuals. Sharing our experiences is not only important for healthy aging but is a crucial process for well-being throughout an individual's life. For people who have been diagnosed with life-threatening or chronic illnesses, sharing illness-related memories also helps them cope with the difficulties associated with the illness. We conducted two studies to understand whether the reasons for sharing memories with others (i.e., reminiscing) are associated with the mental health of adults diagnosed with life-threatening or chronic illnesses. The first study was conducted with 420 young and middle-aged adults from Turkey and found five main purposes of memory sharing: understanding oneself and one's behaviors (i.e., reflection), feeling a sense of fulfillment and leaving a legacy (generativity), interacting with others (social stimulation), bringing memories of difficult times back to mind (bitterness revival), and keeping memories of lost ones alive (intimacy maintenance). Study 2 was conducted with adults who had been diagnosed with a life-threatening illness (e.g., cancer) or a chronic illness (e.g., Type I diabetes). Study 2 indicated that for people living with an adverse life experience such as a chronic illness, sharing memories related to the illness for meaning making, problem-solving, death preparation, informing others, and ruminative purposes is related to depression, anxiety, and regulating associated negative emotions. In contrast, sharing these memories for socializing with others is related to experiencing positive changes after trauma.