Seribu Hari Pertama Kehidupan mencakup 270 hari kehamilan dan 730 hari pertama setelah kelahiran anak. Perkembangan psikososial anak merujuk pada proses pertumbuhan dan perkembangan anak dalam aspek psikologis dan sosial. Perkembangan emosi, kognitif, sosial, dan perilaku anak dengan berjalannya seiring waktu. Penelitian ini bertujuan untuk mengidentifikasi gambaran pengetahuan ibu tentang 1000 hari pertama kehidupan terhadap perkembangan psikososial anak. Penelitian ini merupakan penelitian kuantitatif dengan pendekatan deskriptif, sampel penelitian berjumlah 211. Metode purposive sampling. Penelitian ini menggunakan kuesioner perkembangan psikososial anak usia 0 - 24 bulan yaitu Bayley Scales Infant and Toddler Development (BSID) edisi III skala sosial emosional 24 item. Hasil penelitian menunjukkan mayoritas responden Ibu berusia 30 tahun, tingkat pendidikan terakhir lulusan SMA (62,1%), pekerjaan Ibu rumah tangga (75,4%), berpendapatan kurang dari Rp.5.000.000 per bulan sebanyak (81%), kelahiran anak normal (69,2%), dan status gizi anak normal (98,1%). Hasil penelitian ini mengidentifikasi bahwa pengetahuan ibu tentang 1000 HPK dalam kategori baik dengan prevalensi (41,2%) dan perkembangan psikososial anak berdasarkan usia 0 – 24 bulan memiliki perkembangan psikososial yang normal sebanyak 175 anak (82,94%).

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The First Thousand Days of Life covers the 270 days of pregnancy and the first 730 days after the birth of a child. Child psychosocial development refers to the process of child growth and development in psychological and social aspects. Children's emotional, cognitive, social and behavioral development over time. This study aims to identify a picture of mothers' knowledge about the first 1000 days of life on children's psychosocial development. This research is quantitative research with a descriptive approach, the research sample is 211. Purposive sampling method. This study used a questionnaire on the psychosocial development of children aged 0 - 24 months, namely the Bayley Scales Infant and Toddler Development (BSID) III edition, social emotional scale, 24 items. The results showed that the majority of respondents were mothers aged 30 years, the highest level of education was a high school graduate (62.1%), occupation was housewife (75.4%), income was less than IDR 5,000,000 per month (81%), birth normal children (69.2%), and normal children's nutritional status (98.1%). The results of this study identified that mothers' knowledge about 1000 HPK was in the good category with prevalence (41.2%) and the psychosocial development of children based on age 0 - 24 months had normal psychosocial development as many as 175 children (82.94%).