This Performance assessment instruments to measure 21st century competencies, namely 4C (critical thinking, creativity, collabor). The instrument can be used as a measuring tool in determining the achievement of competencies expected in the 21st centuryation, and communication). Critical thinking, creativity, collaboration, and communication competence can be integrated in STEM learning from an early age. The purpose of this study is to develop a 4C performance assessment instrument that can be used for measuring tools in STEM-based learning in elementary schools. The method that has been used is Educational Design Research (EDR) according to Mc Kenney and Reaves through three stages namely Analysis and Exploration, Design and Construction, and Evaluation and Reflection. This study included 11 observers who observed 5 students as samples. Data collection was conducted by means of interviews, expert judgment and questionnaire entries. The results of the study are instruments of student performance assessment. This instrument is used as an assessment tool that can be used to assess student performance that includes criteria, achievement scores, and descriptions of achievement scores. This development of performance appraisal instruments can be used as a form of assessment because most of the results show Asymp. Sig< 0.05 which is categorized as alignment. This 4C performance assessment instrument is expected to be used in general in conducting performance assessments that measure 21st century competencies in STEM learning.