This chapter begins by defining dependability as the ability of a system to deliver a service while avoiding service failures that are more frequent and more severe than what is acceptable. Faults, errors and failures are threats to dependability of systems. To withstand the disruptive digital storms of the future, enterprise architecture affects digital transformation of the overarching dependability aspects through all the constituting attributes of enterprise architecture, namely, interoperability, scalability, availability, mobility, ubiquity, security, analyticity, and usability—but reliability is an essential pre-requisite to enable this transformation. The chapter’s appendix begins with system reliability’s definition, its characteristics followed by mathematical modeling of reliability. The basic component structures for system reliability, namely, series and parallel relationships are explained—any complex system configuration can be decomposed by using a combination of these two basic structures. This is followed by discussion on reliability (the probability of success for a given period of time), with exponential failures used as the failure distribution functions. In the last part, practical methods and tools for design for reliability in the system life cycle are discussed including Failure Mode Effect Analysis (FMEA) and Faulty Tree Analysis (FTA).