In finite samples, these unit root test procedures are known to have limited power against alternative hypotheses with highly persistent deviations from equilibrium. Simulation exercises also indicate that this problem is particularly severe for small samples (see Campbell and Perron, 1991). This paper considers pooling cross-section time series data as a means of generating more powerful unit root tests. The test procedures are designed to evaluate the null hypothesis that each individual in the panel has integrated time series versus the alternative hypothesis that all individuals time series are stationary. The pooling approach yields higher test power than performing a separate unit root test for each individual.