Effectance motivation—an urge for certainty and a feeling of being able to know, predict, and control one's environment—was initially proposed as the mechanism underlying attitude similarity effects on attraction. However, this motivation was discarded as an explanation when positive affect was identified. The presence of alternative mechanisms did not deny a role for the validation of attitudes in attraction. Therefore, we investigated the validation of one's views by those of peers as an additional mediator and its relation with two previously known mediators of positive affect and trust. As hypothesized, validation mediated attitude similarity effects when measured alone (Experiment 1) and within sequential mediation patterns involving positive affect (Experiment 2A) and trust (Experiments 2B and 2C).