Harris continues by linking his interpretation of Penfield's experiments to the work of Eric Berne, whose model of psychotherapy is based on the idea that emotionally intense memories from childhood are ever-present in adults.

Their influence can be understood by carefully analysing the verbal and non-verbal interchanges ('transactions') between people, hence Berne's name for his model: Transactional Analysis.

Harris sees great merit in the ability of TA to define basic units through which human behaviour can be analysed—the 'strokes' that are given and received in a 'transaction' between two or more people—and a standardised language for describing those strokes.

Harris answers this through a simplified introduction to TA, explaining Berne's proposal that there are three states into which a person can switch: the Parent, the Adult and the Child.

Harris describes the mental state called the Parent by analogy, as a collection of "tape recordings" of external influences that a child observed adults doing and saying.

The emphasis of the book is helping people understand how their life position affects their communications (transactions) and relationships with practical examples.

Harris suggests that crossed transactions are problematic because they "hook" the Child ego state of one of the participants, resulting in negative feelings.

Harris suggests that awareness of this possibility, through TA, can give people a choice about how they react when confronted with an interpersonal situation which makes them feel uncomfortable.

The second half of the book begins by briefly describing the six ways that TA practitioners recognize individuals use to structure time, to make life seem meaningful.

Harris continues by offering practical case studies showing applications of TA to marriage and the raising of both children and adolescents.

Having described such a structured method of dealing with the challenges of human psychology, the final two chapters of the book discuss the question of improving morality and society.

Starting from his axiomatic statement I'm OK, You're OK, he acknowledges that accepting it at face value raises the same philosophical dilemmas as the problem of evil does for believers in a just, omnipotent God.

The work of Wilder Penfield concerning human memory, which appeared to Harris to give TA special credibility because it implied a direct association with neuroscience, has not proved readily repeatable.