RESUMEN
The Scale of Positive and Negative Experience (SPANE) aims to measure affect with high transcultural validity. The bifactor model is the best theoretical option to represent affective balance, although it is not typically used in validation studies. The objectives of this research were to test a bifactor model vis-à-vis the traditional model composed of two correlated factors, to prove its invariance across sexes, and to provide evidence of concurrent validity. A nonprobability sample composed of 600 Mexican students of psychology and medicine was recruit. One-group and multigroup confirmatory factor analyses were carried out. The SPANE and the scales selected to assess depression, perceived stress, and satisfaction with life were applied. The bifactor model showed better goodness-of-fit indices than the two correlated factors model: Δχ2(11) = 121.436, p < . 001, Δχ2/Δdf = 11.04 > 5, ΔGFI = .034, ΔNFI = .025, ΔNNFI = .022, and ΔCFI = .023 >.01. The internal consistency for the general factor as well as for the factor of positive affect was excellent, whereas it was good for the factor of negative affect. The measurement model was valid across sexes. The general factor of affective balance had a very high correlation with depression, high with perceived stress, and medium with satisfaction with life. It is concluded that SPANE is reliable and shows evidence of validity among Mexican student of psychology and medicine, and the bifactor model is adequate to represent affective balance.