An account is given of how a clinician guided by attachment theory approaches the clinical conditions to which the theory is held to apply, which include states of anxiety, depression and emotional detachment. Assessment of a patient is in terms of the patterns of attachment and caregiving behaviour which he commonly shows and of the events and situations, both recent and past, which may have precipitated or exacerbated his symptoms. The problems posed by relevant information being suppressed or falsified are noted. Viewed in this perspective a psychotherapist is seen to have a number of inter-related tasks: (a) to provide the patient with a secure base from which he, the patient, can explore himself and his relationships; (b) and (c) to examine with the patient the ways in which he tends to construe current interpersonal relationships, including that with the therapist, and the resulting predictions he makes and actions he takes, and the extent to which some may be inappropriate; (d) to help him consider whether his tendencies to misconstrue, and as a result to act misguidedly, can be understood by reference to the experiences he had with attachment figures during his childhood and adolescence, and perhaps may still be having.