Establishing a relationship is considered the foundation of providing person-centred care (PCC) when working with a person who has a diagnosis of dementia. Currently, there is a lack of consensus about the how to develop this relationship. This aim of this study was to explore the key skills adopted by clinicians to establish an effective care relationship, referred to as therapeutic alliance, specific to working with patients who have dementia. Participants were clinicians (nursing and allied health professionals) from two older person’s mental health service teams (inpatient and community) who routinely provided clinical care to patients with a diagnosis of dementia. Participants self-selected from a purposive sample to complete a semi-structured interview about their provision of care to, and strategies used to engage with, people with a diagnosis of dementia. Exploratory qualitative thematic analysis was conducted using mixed inductive and deductive procedures. Five themes were identified as the interpersonal skills used to develop relationships with patients including the following: empathy, unconditional positive regard, congruence, psychological flexibility, and communication. Findings from this study provide direction for training of clinicians employed in a dementia setting and can also be generalized to other non-specific clinical settings where clinicians may incidentally provide treatment to patients with a diagnosis of dementia.