As a result of the quick rise of pXRF technology in archaeology, there are concerns regarding the reliability and validity of data output acquired from pXRF. In this study, I test the hypothesis that portable X-ray fluorescence (pXRF) spectrometry can provide reliable and valid results, using newly developed calibration curves, for the analysis of archaeological animal and human skeletal materials in prehistoric Peru to address hypotheses about ancient diet and trade. While pXRF systems may come with calibration software, the few if any standards and reference materials provided with the instrument rarely correspond to the vast array of archaeological materials capable of being analyzed by pXRF, including archaeological bone specimens. Empirical calibration curves for Ba, Ca, Fe, and Sr were created using the linear regression analysis of 19 human and animal bone standards analyzed via pXRF and ICP-MS. The results suggest the calibrations for Ca and Sr are sound, but the calibrations for Ba and Fe need to be further improved. In order to assess the reliability of pXRF (i.e. precision and accuracy), statistical analyses of 60 measurements on human bone specimens as well as on 19 human and animal bone specimens was performed in this study. The results indicate that the precision of pXRF is reliable, but additional work is needed with regard to accuracy. In contrast, the analysis of forty-four prehistoric human and animal bone specimens from varying regions in Peru were used to test the validity of pXRF. The pXRF data support the notion that pXRF is a valid technique to use in the analysis of bone specimens to address archaeological questions regarding paleodiet and possible trade interactions among individuals that reside in the highland and coastal valley regions of Peru