For a psychological test to be considered valid, it needs to exhibit specific psychometric properties, with internal validity being the most significant among them. The objective of this study is to analyze the internal validity of the score of the STAI questionnaire, which was created by Spielberg in 1964 with the aim of measuring the construct of state anxiety and trait anxiety. 97 participants completed the STAI questionnaire, and the obtained results were analyzed using two different statistical methods: factorial analysis and network analysis. It was hypothesized that the factorial structure identified in the data collected form the questionnaire aligns with the arrangements proposed by Spielberg in 1964. This arrangements involves a two- factor internal structure, with one factor capturing state anxiety and the other representing trait anxiety. The results revealed a two-factor structure for the STAI questionnaire, thus confirming the structure initially proposed by Spielberger in 1964. Regarding the state anxiety scale, a two- factor structure emerged, however, it does not reflect the dimensionality highlighted in the literature. Regarding the trait anxiety scale, analyses revealed a two-factor structure that is in agreement with the structure highlighted in the literature. Afterwards, an abbreviated version of the STAI questionnaire was developed with the most representative items of the state anxiety and trait anxiety constructs. This version revealed a four-factor structure. In conclusion, the analysis of the internal validity of the STAI questionnaire revealed structures that diverge from those proposed in the literature, suggesting alternative interpretations of the construct.