Introduction: Intrafamily relationships are defined as the interconnections developed between family members. They involve aspects such as family unity, family coping styles, emotion expression, and management of family coexistence norms. The Intrafamilial Relations Assessment Scale (IRA) has proven to be a reliable instrument for measuring this variable. However, few validations have been conducted in Latin American contexts. Aim: Analyze the psychometric properties of the intrafamilial relationships assessment scale in high school students. Method: An instrumental study was conducted including 315 students from a public University in Jalisco, Mexico. The intermediate version of the Intrafamilial Relationships Assessment Scale was applied. Exploratory and confirmatory factor analyses were performed. Results: The final model consisted of 10 items grouped in two dimensions with adequate fit indices X2/gl = 0.74, CFI = .991, SRMR = .024, RMSEA = .038 [.015, .058]. Evidence of convergent and divergent validity, as well as invariance by sex, was also found. Discussion: The assessement scale is a valid and reliable instrument to evaluate the dimensions of Unity, support and expression, as well as the perception of Family difficulties