This study focused on examining the relationships between stress, resources, and adjustment of Chinese married mothers and fathers following childbirth. Guided by a generic theoretical model of parenthood transition, the aim of the current study was threefold. First, longitudinal data were collected to clarify the impact of parenthood from 6 weeks postnatal (Time 1) to 6 months postnatal (Time 2). A diachronic design is more advantageous in making causal inferences as baseline levels of mental health and marital satisfaction can be controlled. Second, a gender‐balanced design was adopted to examine the transition processes for both men and women to overcome our shortcomings in understanding men's experiences. Third, this study was conducted in a Chinese society to examine the transition to parenthood as embedded in this particular cultural context. A total of 483 parents (253 females, 230 males) took part in this two‐wave panel study. Hierarchical multiple regression analyses and structural equation modelling techniques were used to test for direct, moderation, and mediation effects of marital congruence and social support as resources. Results showed that (a) parental stress had negative effects on mental health and marital satisfaction, and these relationships were robust across time and gender; (b) marital congruence and social support had direct as well as mediation effects on adjustment; (c) marital congruence also had moderation (stress buffering) effects on the stress/mental health relationship; (d) over the half‐year period, there were no significant changes in stress and adjustment outcomes, yet marital congruence and social support significantly declined, and this trend was the same for both sexes; (e) although males and females did not differ in marital congruence and social support, women reported higher stress, more psychological symptoms, and lower marital satisfaction than men. These gender differences did not change over time. These results were discussed in relation to existing theories and research, as well as the distinct characteristics of the contemporary Chinese society.