Background: Trisomy 13 and trisomy 18 are common life-limiting conditions associated with major disabilities. Many parents have described conflictual relationships with clinicians, but positive and adverse experiences of families with healthcare providers have not been well described. Aim: (1) To investigate parental experiences with clinicians and (2) to provide practical recommendations and behaviors clinicians could emulate to avoid conflict. Design: Participants were asked to describe their best and worse experiences, as well as supportive clinicians they met. The results were analyzed using mixed methods. Setting/participants: Parents of children with trisomy 13 and 18 who were part of online social support networks. A total of 503 invitations were sent, and 332 parents completed the questionnaire about 272 children. Results: The majority of parents (72%) had met a supportive clinician. When describing clinicians who changed their lives, the overarching theme, present in 88% of answers, was trust. Parents trusted clinicians when they felt he or she cared and valued their child, their family, and made them feel like good parents (69%), had appropriate knowledge (66%), and supported them and gave them realistic hope (42%). Many (42%) parents did not want to make—or be part of—life-and-death decisions. Parents gave specific examples of supportive behaviors that can be adopted by clinicians. Parents also described adverse experiences, generally leading to conflicts and lack of trust. Conclusion: Realistic and compassionate support of parents living with children with trisomy 13 and 18 is possible. Adversarial interactions that lead to distrust and conflicts can be avoided. Many supportive behaviors that inspire trust can be emulated.