This study explores and compares the rationales behind, and justifications for, intentions about whether or not to have a second child among Polish fathers and mothers living in the UK and Poland. Drawing on semi-structured interviews (n=42) contextualised by media and statistical analyses, the thesis interrogates the Theory of Planned Behaviour (TPB) and explores the extent to which aspects related to the theory (i.e. attitudes, subjective norms and perceived behavioural control) permeate informants’ narratives. This thesis emphasises that researching fertility intentions requires more complex and context-specific operationalisations of theoretical constructs as drawing on standardised definitions and concepts across different populations could impact data validity and reliability, and I suggest ways in which survey questions could be modified. The findings demonstrate the importance of transnational groups of reference for Polish individuals’ understanding of resources deemed as adequate to have a second child, suggesting that the notion of economic wellbeing is more variable and complex than current evidence suggests. The study also illustrates that kin assistance in Poland is relevant for reproductive decisions since it relates to economic constraints to childbearing and to perceived requirements to provide children with kin support and inheritance. Moreover, individuals in both settings communicate beliefs related to childbearing intentions discursively, fine-tuning ambivalent and inconsistent cognitions while constructing a coherent narrative. The findings question the TPB assumption that people reach decisions primarily as a result of causal, regular and law-governed forces acting on theoretical constructs independent of individuals’ agency, and I point to possibilities to expand and refine theories used in demographic research. Although my empirical findings focus on Polish nationals, I argue that this research has broader implications for theorising, researching and interpreting findings on childbearing intentions.