In this paper, I will highlight the key aspects that emerged as fundamental in the context of weekly psychoanalytic psychotherapy with a four-year-old girl, following some reflections on the concept of cumulative trauma in psychoanalytic thought, with particular attention to Masud Khan’s contribution. This therapy involves various levels of engagement and processing of individual and familial traumatic experiences. Early cumulative traumas, occurring during the very first stages of development, may become embedded in the mind, as they happen during phases in which the capacity for representation has not yet developed. Through the presentation of clinical material, this work demonstrates how the processing of countertransference – when dealing with such complex psycho-sensorial experiences that are challenging to approach, hold in mind, and work through – creates new opportunities for growth and change within the therapeutic relationship.