In this work, we formalize the concept of naturalness in supersymmetric effective field theories, as well as introduce novel methods for performing statistical analyses in the string landscape. We revisit the various measures of practical naturalness for models of weak-scale supersymmetry (SUSY) including: 1. electroweak (EW) naturalness; 2. naturalness via sensitivity to high-scale (HS) parameters [Ellis-Enquist-Nanopoulos-Zwirner/Barbieri-Giudice (EENZ/BG)]; 3. sensitivity of Higgs soft terms due to high-scale radiative corrections; and 4. stringy naturalness (SN) from the landscape. We debut a new numerical routine for calculating these measures from any SUSY Les Houches Accord file. A vast array of (metastable) vacuum solutions arise from string compactifications, each leading to different 4-d laws of physics. The space of these solutions, known as the string landscape, allows for an environmental solution to the cosmological constant problem. We argue that the landscape favors natural softly broken supersymmetric (SSB) models over particle physics models containing quadratic divergences, such as the Standard Model or unnatural SSB models by presenting a computable measure. An anthropic selection of the weak scale to within a factor of a few of our measured value — in order to produce complex nuclei as we know them (atomic principle) — provides statistical predictions for Higgs and sparticle masses in accord with LHC measurements. The predicted Higgs and superparticle spectra might be testable at HL-LHC or ILC via higgsino pair production but is certainly testable at higher energy hadron colliders with s∼ 30–100 TeV.