Drawing on a qualitative survey administered to 70 separated parents, this article focuses on organisational changes in the residential arrangements of children following a separation. Behind the apparent legal and statistical stability of residence modes lie informal adjustments between ex-partners informed by daily contingencies. The adjustments are based on three tacit prerequisites – anticipation, reciprocity and calmer relations – but also depend on material conditions that weigh on the arrangements. An analysis of the shift, less common, from one residential mode to another, reveals a gradation of situations ranging from a consensual decision by the parents to clashes over the residence of the children. An assessment of the justifications for these organisational changes points to a rhetoric of “good parenting” in the context of separations. The desire to “do one’s best” for the child is the most predominant justification for the interviewees. This altruistic norm of doing things “in the interest” of the child is cited by men as often as it is by women and corresponds to three main acceptations: respecting the principle of coparenting, favouring the unity of siblings and listening to one’s child. Other, more personal registers, assumed to a varying degree, also play a part, such as occupational reasons, the reforming of a couple and, more rarely, accusations of the disinvestment of the other parent.