Research on interest group appearances in parliamentary committees has provided extensive evidence about the factors and conditions that explain their access and interaction with MPs. However, the extent to which legislators align with interest groups interventions has received less attention. This paper contributes both theoretically and empirically to the analysis of interest group interactions with legislators by measuring the degree of alignment between them during parliamentary hearings. Specifically, we examine the extent to which legislators' responses to interest group appearances are aligned, thus converge in their viewpoints, arguments, and justifications concerning a particular issue or policy. Alignment is operationalized as semantic similarity, using phrase embeddings for an original dataset on hearings in the Spanish parliament between 1993 and 2023. This analytical approach offers a nuanced perspective that complements extant evidence derived from text analysis on lobbying reports, executive consultations, press releases, parliamentary debates and social media data in a longitudinal perspective. After controlling for several confounding variables, our results show that the type of group and the policy making activity under discussion shapes the alignment among interest groups and parliamentary groups. Insights from the dynamics between interest groups and parties in the legislative process are relevant in the study of pluralism and interest representation and their role in societal transformation.