Marriage is usually the gateway to adulthood for young women, once they find suitable partners. In some cases, for various reasons, women have to live with their parents-in-law after marriage. This can cause the subjective well-being of wives who live with their parents-in-law to be disturbed. Several previous studies have shown the role of self-differentiation on subjective well- being, but it is still very minimal, especially in Indonesia, and there has been no research on wives who live with their parents-in-law. So, it is important to examine the role of self- differentiation on the subjective well-being of wives who live with their parents-in-law. This research was conducted on wives who live with their parents-in-law, using a self-differentiation measuring instrument with 20 items, Chronbach Alpha 0.842, PANAS (Positive Affect Negative Affect Schedule) a total of 20 items, Cronbach Alpha 0.826 (positive affect) and 0.854 (negative affect); and SWLS (Satisfaction with Life Scale) 5 items with Chronbach Alpha 0.896. Data analysis from 108 participants (Mage=42.47, SD=8.28, Min=23, and Max=68) obtained through convenience sampling and snowball sampling techniques resulted in a significant role of self-differentiation (b=0.454, p<0.001) on SWB of 30.1%. Further analysis through examination of each dimension of self-differentiation, found that there was a significant positive relationship with moderate strength between the I-Position dimension and SWB. Meanwhile, the EC dimension and the ER dimension towards SWB, there was a significant negative relationship of moderate strength. / Pernikahan biasanya menjadi gerbang menuju dewasa bagi wanita muda segera setelah dia menemukan pasangan yang sesuai. Tak jarang, wanita harus tinggal bersama mertua setelah menikah, karena berbagai alasan. Hal ini bisa menyebabkan kesejahteraan subjektif istri yang tinggal bersama mertua terganggu. Beberapa penelitian sebelumnya menunjukkan peran diferensiasi diri terhadap kesejahteraan subjektif, namun masih sangat minim terutama di Indonesia, dan belum ada penelitian terhadap istri yang tinggal bersama mertua. Sehingga dirasa penting untuk meneliti peran diferensiasi diri terhadap kesejahteraan subjektif istri yang tinggal bersama mertua. Penelitian ini dilaksanakan terhadap istri-istri yang tinggal bersama mertua, menggunakan alat ukur diferensiasi diri dengan 20 item, Chronbach Alpha 0.842, PANAS (Positive Affect Negative Affect Schedule) total 20 item, Cronbach Alpha 0.826 (afeksi positif) dan 0. 854 (afeksi negatif) dan SWLS (Satisfaction with Life Scale) 5 item Chronbach Alpha 0.896. Analisa data 108 partisipan (MUsia=42.47, SD=8.28, Min=23, Max=68) yang diperoleh melalui teknik convenience sampling dan snowball sampling menghasilkan peran diferensiasi diri yang signifikan (b=0.454, p<0.001) terhadap SWB sebesar 30.1% Selain itu melalui uji tiap dimensi diferensiasi diri ditemukan ada hubungan positif signifikan dengan kekuatan sedang antara dimensi I-Position dengan SWB Sedangkan dimensi EC dan dmensi ER terhadap SWB terdapat hubungan negatif signifikan dengan kekuatan sedang.