Abstracts The pursuit of happiness is not merely a personal endeavour but also a societal imperative, influencing governmental policies and individual well-being. In the realm of economics, the correlation between income and happiness has long been a subject of scrutiny, particularly the phenomenon known as the income paradox. This paradox, first highlighted by Easterlin in 1974, questions why despite rising incomes, average happiness levels often remain stagnant. Numerous studies have since delved into this puzzle, with a predominant focus on relative income and income inequality. However, there remains a notable research gap on this subject in transitional countries, especially Vietnam. This thesis aims to enrich the empirical study of the influence of income on subjective well-being, in part to elucidate the income - happiness paradox in Vietnam. This thesis includes three papers. The first paper employs panel data sourced from the Viet Nam Access to Resources Household Survey (VARHS), spanning three periods — 2012, 2014, and 2016. Utilising fixed effect estimates, it assessed the impact of absolute income and three specifications of external comparison income on individual happiness. The focal point of this paper lies in categorizing subgroups based on relative income rather than absolute income. This approach enables the removal of conflicting relationships, allowing for a clearer understanding of how social comparison income influences individual happiness. Findings suggest that individuals compare themselves to multiple reference groups, both upwards to those better off and downwards to those worse off. However, statistically significant results emerge only when one comparison outweighs the other, or when both comparisons align either upward or downward impact. Intriguingly, the outcome shifts from asymmetry to near symmetry when the interactive effects among reference groups change from opposition to alignment. The second paper presents a pioneering investigation into the impact of self-perceived economic status on subjective well-being. This study employs panel data sourced from VARHS, covering three periods: 2016, 2018, and 2020. By employing fixed effect estimates, it investigates the dynamic interplay between absolute and relative self-perceived household economic status within the commune and subjective well-being. This exploration is conducted by applying four primary specifications and an analysis of the interaction between increases in per capita income and shifts in household economic status. The findings reveal that present self-perceived economics status positively influences personal happiness, while past self-perceived economics status has the opposite effect. Additionally, the influence of comparisons between present and past self-perceived relative income can exhibit symmetry or asymmetry, depending on the approach. Moreover, a positive relationship is identified between the distance in a household's current and past economic household rank and individual happiness. External comparison is asymmetrical and is a stronger factor than internal income comparison. Despite an increase in absolute income, overall personal SWB is not guaranteed to rise, underscoring the pivotal role of the perception of household economic position or relative income in determining individual happiness. The third and final paper represents one of the earliest studies to examine the influence of self-perceived income inequality on life satisfaction, employing an instrumental variable approach. It is also a pioneering study in utilising data from the VARHS of 2020 in investigating the effects of self-perceived income inequality on life satisfaction in Vietnam. The results highlight the adverse impact of perceived income inequality on individuals' overall life satisfaction, with controls for endogeneity further emphasizing this effect. These findings underscore the importance of government initiatives aimed at reducing economic disparities to enhance individual subjective well-being.