抑郁和焦虑等内化问题高发于青少年时期，是初中阶段发生率最高的一种心理健康问题，不仅有碍于青少年当下的学校适应、学业成绩和幸福感等，还有可能延续到下一个发展阶段并导致更为严重的心理疾病。鉴于其高发性和高危害性，不少研究者从人际关系的角度探讨了青少年内化问题的产生机制，为内化问题的筛查和干预提供了一定的理论支持和实证依据。然而，这些研究主要停留在静态层面的关系质量上，忽视了关系质量的波动变化（简称为关系波动）对内化问题的影响。

基于此，本研究选取1030名初一学生，进行为期一年的四次追踪测查，在考察关系质量影响的基础上进一步关注青少年人际关系的动荡变化，综合探讨关系质量与关系波动对青少年内化问题的影响及机制。主要结果如下：

（1）青少年的关系质量会随时间发生波动变化。友谊质量的波动程度显著高于亲子关系波动，而亲子关系波动程度又显著高于师生关系的波动程度。

（2）亲子关系质量通过自尊对抑郁起到保护作用，师生关系质量直接负向预测抑郁，而友谊质量通过情绪失调正向预测抑郁和焦虑。按性别分群体检验关系质量的作用机制发现，师生关系通过自尊降低女生的抑郁和焦虑，友谊质量通过情绪失调影响男生的抑郁和焦虑。

（3）师生关系波动不仅直接预测抑郁，还能通过情绪失调正向预测抑郁和焦虑；友谊质量波动能够通过损害自尊，进而影响青少年的抑郁和焦虑。按性别分群体检验关系波动的作用机制发现，师生关系波动通过增加情绪失调影响女生的抑郁和焦虑，友谊质量波动则通过降低男生自尊的方式发挥作用。

Internalizing problems are highly prevalent among adolescence. One meta-analysis found that internalizing problems are more prevalent in middle school than other mental health problems. Alarmingly, internalizing problems undermine adolescents' developmental outcomes in the present (i.e., school adjustment, academic performance, and well-being) and can carry over to the next developmental stage and cause more serious psychological disorders. Given the high prevalence and harmfulness of adolescent internalizing problems, numerous studies have explored the mechanisms of adolescent internalizing problems from the perspective of interpersonal relationships. While these studies provided a basis and support for screening and intervention of internalizing problems, there are still some limitations. Specifically, most existing studies examined the association between relationship quality and internalizing problems at the between-person level, ignoring that relationship quality fluctuates during adolescence; thus, it remains to be seen whether and how relationship fluctuation influences internalizing problems.

The current study selected 1030 first-year students to examine the association between relationship quality, relationship fluctuation, and internalizing problems with a four-wave longitudinal design to address the abovementioned limitations. Based on the emotion dysregulation model and the self-esteem theories of depression, we further explored the mediation mechanism of emotion dysregulation and self-esteem, with particular attention to the potential gender differences in the mechanism. The main results were as follows:

(1) The relationship qualities among adolescents fluctuates over time. Friendship quality fluctuated significantly more than parent-child relationship quality, which in turn fluctuate significantly more than teacher-student relationship quality.

(2) The mechanisms by which different relationship qualities affect adolescents' internalizing problems differ. Parent-child relationship quality protects against depression through self-esteem, teacher-student relationship quality directly negatively predicts depression, and friendship quality positively predicts depression and anxiety through mood dysregulation. Additionally, there were gender differences in the mediation mechanism in the association between relationship qualities and internalizing problems. Among boys, parent-child relationships reduced depression by increasing self-esteem, but friendship quality increased their risk of depression and anxiety through emotion dysregulation. Among girls, parent-child relationships reduced depression through self-esteem, and teacher-student relationships reduced depression and anxiety through self-esteem.

(3) Relationship qualities fluctuated over time, exacerbating adolescents' internalizing problems. Specifically, teacher-student relationship fluctuations directly predicted depression and positively predicted depression and anxiety through emotion dysregulation; friendship quality fluctuations impaired adolescents' self-esteem, affecting their depression and anxiety. The mediation mechanisms in the associations between relationship fluctuations and internalizing problems differed by gender. Among boys, friendship quality fluctuations increased their depression and anxiety by lowering self-esteem. Among girls, teacher-student relationship fluctuations influenced their depression and anxiety by increasing emotion dysregulation.