For over 45 years, research investigating Machiavellianism has largely used the same unidimensional approach, even though empirical research demonstrates that Machiavellianism is comprised of 2 robust dimensions: views and tactics. This article elaborates on the theory and conceptualization behind the 2 dimensions. It also documents the construction and validation of the 12-item Two-Dimensional Machiavellianism Scale (TDMS), which measures the cynical and untrusting views dimension, and the immoral interpersonal tactics dimension, across 6 samples (N = 3,886, 37.70% men) using confirmatory factor analysis (CFA) and item response theory. The 2-factor structure fitted the data well based on CFA, and was invariant across samples, gender, and over a 3-month period (N = 338, 36.39% men). Evidence of each subscale's construct validity was established using structural equation modeling. As expected, the Views subscale was primarily associated with misanthropy, hypersensitive narcissism, lower subjective well-being, and lower emotional stability. The Tactics subscale was primarily associated with psychopathy, lower conscientiousness, lower willingness to reciprocate, and "ends justified the means" behavior in ethical dilemmas. The TDMS enhances practical and conceptual understanding of Machiavellianism through demarcating the underlying motivations and addresses the need for an updated and psychometrically sound measure of Machiavellianism. (PsycINFO Database Record (c) 2020 APA, all rights reserved).