Background: Extant research has traditionally associated children's achievement motivation with socio-emotional parental behaviours such as demonstrations of affect, responsiveness, and the degree of parental control. Aims: This study explored the extent to which parental socio-emotional and instructional behaviours (including the contingency of instructional scaffolding) both related to children's mastery and performance tendencies towards homework-like activities. Sample: The study involved nine underachieving primary-aged children and their parents, with four children showing predominantly mastery-oriented behaviours in the homework context and five showing predominantly performance-oriented behaviours. Methods: An in-depth observational analysis of video-recorded parent-child interactions during four homework-like sessions was carried out for each case. Socio-emotional and instructional parental behaviours were coded and subjected to nonparametric quantitative analyses. Subsequently, thick descriptions of parent-child interactions were used to identify critical aspects of parental assistance. Results: Moderate cognitive demand was associated with mastery orientation, while negative affect was related to performance orientation. As revealed quantitatively and qualitatively, socio-emotional and instructional parental behaviours were also associated with each other, forming distinct profiles of parental behaviours related to children's homework motivation. Conclusions: The findings support the idea that instructional parental behaviours are as important as socio-emotional ones in the analysis of children's homework motivation. The value of observational methods in investigating the target variables is discussed.