The study developed a set of items that measure University undergraduatesâ€™ Self-compassion using Latent Trait Theory framework and it ascertained the construct validity of the developed scales. These were with the view of providing a reliable and suitable instrument to measure University Undergraduatesâ€™ Self-compassion. The study employed the descriptive survey design. The population was comprised of undergraduates in South-western Nigeria universities. The sample size was 2250 students selected through a multi stage sampling procedure. The research instrument was a self-developed University Undergraduatesâ€™ Self-Compassion Scale. Data were analysed using multidimensional item response theory, graded response model, factor analysis, Cronbach Alpha Coefficient and empirical reliability estimate approach. The results showed the LTT psychometric procedures of item retention and deletion reduced the 93 - item UUSCS to 21 items with five interpretable factors. The results also showed with the high convergent and discriminant validity, the five factor 21-item LTT developed UUSCS had high construct validity and reliability (r =0.89). The study indicated the Latent Trait Theory developed University Undergraduatesâ€™ Self-Compassion Scale is a reliable and suitable instrument for the measurement of university undergraduatesâ€™ self-compassion.