A study was conducted to compare the quality of the item parameter estimates obtained from the ANCILLES and LOGIST estimation procedures using goodness of fit as a criterion. Statistics used to compare the fit included a chi-square statistic and a mean square deviation statistic. Other analyses performed included comparisons of the distributions of the parameter estimates obtained from the procedures, and a set of meta-analyses performed on the chi-square statistics obtained for the items. The data for the study were composed of 50 items and 2,000 cases obtained using a stratified random sample of 357 items and 4,000 cases of the Iowa Tests of Educational Development. Results indicated that there are qualitative differences in the estimates obtained from these two procedures. While the parameter estimate distributions obtained from these two procedures were similar, lack of fit occurred for significantly more items for ANCILLES than for LOGIST. Lack of fit for ANCILLES appeared to be stongly related to item difficulty, while for LOGIST it was related to item discrimination. Although LOGIST is more expensive to use than ANCILLES, ANCILLES yielded lack of fit significantly more often than LOGIST, and did not yield item parameter estimates for two items. (Author/RL)