Children from substance‐misusing families face elevated risks in growing up well and safe. Early intervention is an opportunity for local authorities to offer support and keep a watching brief on children's welfare. However, the basis upon which agencies voluntarily engage with families in advance of major problems becoming evident is far from straightforward. This qualitative pilot study in Scotland followed professional decision‐making over 6 months (n = 20 professionals) with a small number of families (n = 6) defined as in need of supportive intervention. This support was allied with an intention to monitor the family situation, which, in these data, appeared to affect the willingness of families to engage with services. As services sought to increase their voluntary oversight, sometimes by threatening escalating involvement, so families by various means appeared to resist it. Successful early intervention is reliant on voluntary family participation and thus requires close attention to means of positive and motivated parental engagement to disarm resistance.