This paper analyzes collective bargaining using Spanish firm level data. Central to the analysis are the joint determination of wage and strike outcomes in a dynamic framework and the possibility of segregate wage equation for strike and non-strike outcomes. Conditional to strikes taking place, we confirm a negative relationship between strike duration and wage changes in a dynamic context. Furthermore, we find selection in wage equations induced by the strike outcome. In this sense, the possibility of wage determination processes being different in strike and non-strike samples is not rejected by the data. In particular, wage dynamics are of opposite sing in both strike and non-strike equations. Finally, we find evidence of a 0.33 percentage points wage change strike premium.