The main goal of this method paper was to evaluate the reliability and factorial validity of flexibility tests used in soccer, and to do crossvalidation study on 2 other team sports using handball and basketball players. The second aim was to compare the validity of the different tests and evaluate the flexibility of soccer players; the third was to determine the positional differences between attackers, defenders, and midfielders in all flexibility tests. One hundred and fifty (n = 150) elite male junior soccer players, members of the First Croatian Junior League Teams, and 60 (n = 60) handball and 60 (n = 60) basketball players also members of the First Croatian Junior League Teams volunteered to participate in the study, tested for the purpose of crossvalidation. The SAR and V-SAR had the greatest AVR and ICC. The within-subjects variation ranged from between 0.3 and 3.8%. The lowest value of CV was found between the LSPL and LSPR. Low to moderate statistically significant correlation coefficients were found among all the measured flexibility tests. It was observed that the greatest correlations existed between the SAR and V-SAR (r = 0.65) and between the LLSR and LLSL (r = 0.56). Statistically significant correlations were also observed between the BLPL and BLPR (r = 0.62). The principal components factor analysis of 9 flexibility tests resulted in the extraction of 3 significant components. The results of this study have the following implications for the assessment of flexibility in soccer: (a) all flexibility tests used in this study have the acceptable between and within-subjects reliability and they can be used to estimate the flexibility of soccer players; (b) the LSPL and LSPR tests are the most reliable and valid flexibility tests for the estimation of flexibility of professional soccer players.