Four internationally-accredited transactional analysis psychotherapists completed semi—structured one-to-one interviews that explored their experiences and sense-making of Internet addiction (IA). Interpretive phenomenological analysis yielded four higher-order concepts: the complexity of IA; aetiological and predisposing factors; functions and features of IA; and treatment factors. Practical and theoretical implications for future research, clinical supervision, treatment, psycho-educational and political programmes are presented. Of the key emergent findings the Internet was understood by participants as a conduit or medium for addiction given a high prevalence of an underlying ‘disorder’. It was also found that participants believed in the existence of childhood aetiological roots underpinning comorbidity with IA; that attachment difficulties in childhood often predispose individuals to develop issues around loneliness, low self-esteem, control, loss, instability and cognitive dissonance later in life; and that a relationship exists between depression, low self-esteem and escapism as contributing factors. It is concluded that professionals would benefit from specific trainings concerning childhood attachment difficulties, whilst integrating a psychodynamic approach, or being aware of transference processes, could enhance treatment effectiveness and help safeguard both clients and therapists from counter-therapeutic interventions.