This report presents reliability, validity and sensitivity indices for the Motivational Interviewing Treatment Integrity (MITI) scale. Factor analysis of MI treatment sessions coded with the Motivational Interviewing Skills Code (MISC) was used to derive 10 elements of MI practice, forming the MITI. Canonical correlation revealed that the MITI captured 59% of the variability in the MISC. Reliability estimates for the MITI were derived using three masked, independent coders. Intra-class coefficients ranged from .5 to .9 and were generally in the good to excellent range. Comparison of MITI scores before and after MI workshops indicate good sensitivity for detecting improvement in clinical practice as result of training. Implications for the use of this instrument in research and supervision are discussed.