Acts of abuse are indicative of a parent's inability to regulate his or her own emotions in an appropriate manner and jeopardize a child's development. Foster care should provide a safe environment both to protect a child from harm and to heal a damaging social-emotional developmental trajectory. How does a child learn to regulate his or her emotions faced with the two different environments of foster home and parental home? This study is based on the use of a microanalytic observation method using a video-recording device in natural settings. It concerns a preschooler, Lola, aged 5, and her birth parents and Foster Mother (FM), who together form her caregivers. To evaluate the evolution of their interactions over a year, three observational sessions were held at an interval of six months. The emotional regulation learning processes used by Lola and her caregivers during playtime were analyzed with Emotion Regulation Strategies (ERS) coding systems in order to build ERS cycles. The analysis of this case showed that Lola learnt to develop language strategies to regulate her emotions with her FM, while exhibiting self-soothing behaviors and distraction strategies with her biological parents. The degree of distress and emotional tension in her birth family had a critical impact on Lola's ERS learning processes. Clinical implications for child care practices are discussed following a clinical psychology perspective.