The intent of this thesis is to examine the psychometric properties of a complex span task (CST) developed to measure working memory capacity (WMC) using measurements obtained from a sample of 68 undergraduate students at the University of Central Florida. The Grocery List Task (GLT) promises several design improvements over traditional CSTs in a prior study about individual differences in WMC and distraction effects on driving performance, and it offers potential benefits for studying WMC as well as the serial-position effect. Currently, the working memory system is composed of domain-general memorial storage processes and information-processing, which involves the use of executive functions. Prior research has found WMC to be associated with attentional measures (i.e., executive attention) and the updating function, and unrelated to the shifting function. The present study replicates these relationships to other latent variables in measures obtained from the GLT as convergent and discriminant evidence of validity. In addition, GLT measures correlate strongly with established measures of WMC. Task reliability is assessed by estimates of internal consistency, pairwise comparisons with a cross-validation sample, and an analysis of demographic effects on task measurements.