This study developed two complementary instruments to assess the social domain in preschool children using two distinct sources of information. The Social Domain Scale Teacher Form measures classroom social behaviors based on teacher observation. The Curiosity about the Social World Scale Child Form measures children's curiosity about people, rules, occupations, and social differences through children's own responses. Data were collected from 500 preschool children aged 48 to 72 months. Six experts reviewed the item pools, and Item-CVI and Scale-CVI values were calculated following Davis (1992) and Polit and Beck (2006). For the teacher form, the sample was randomly split into EFA (n = 250) and CFA (n = 250) subsamples. The teacher form converged on 17 items across three factors. The child form converged on 14 items across four factors. Both forms showed acceptable fit in CFA (teacher form: CFI = 1.000, RMSEA = .000, SRMR = .034; child form: CFI = 1.000, RMSEA = .000, SRMR = .037). Cronbach's alpha for the total scales was .85 and .76, and McDonald's omega was .91 and .87, respectively. Test-retest reliability was assessed over a three-week interval with a subsample of 80 children and their teachers; correlations ranged from .78 to .89 for the teacher form and from .80 to .88 for the child form. The correlation between the two total scores was r = .32. The subscale correlation pattern is consistent with the interpretation that the two instruments measure related but distinct constructs.