Abstract Relationships among selected variables of eggshell quality in broiler breeder eggs were determined over complete production cycles in three experiments. Variables measured were egg weight (EW), egg specific gravity (SG), eggshell weight (SW), water vapor conductance (G), and regional pore concentration (PC) and eggshell thickness (ST) (Experiments 1 and 2). Hatchability was examined in one experiment (Experiment 3). Eggshell weight, ST, and SG were all positively correlated with each other and PC in three regions of the shell (small end, equator, and large end) were highly positively correlated among themselves in Experiments 1 and 2. Pore concentration showed negative correlations with SG and ST but was positively correlated with G and G per 100 g EW (G/EW) in Experiments 1 and 2. Egg weight and shell weight increased with bird age in Experiments 2 and 3; however, negative trends over time were found for SG, PC, G, and G/EW in Experiment 2 and for G/EW and hatchability in Experiment 3. Quadratic regressions were similar for G/EW, hatch of fertile eggs, and hatch of total eggs in Experiment 3. Percentage hatch of fertile eggs peaked at Week 47 and was statistically lower at Weeks 55, 59, and 63, and percentage hatch of total eggs set was statistically lower at Weeks 55 and 59 than at Weeks 35, 39, and 47. It was concluded that eggshell quality changes with bird age. Conductance/egg weight appeared to be a useful indicator of hatchability, and the contribution of reduced G/EW to decreased hatchability was most evident late in production when eggshell surface area to egg volume ratio was lowest.