Tamper-indicating seals are meant to detect unauthorized access, entry, or tampering. For the purposes of this study, a "passive" seal was defined as "never electrified with alternating current or direct current," and an "active" seal, by contrast, is electrified at some point in its use cycle. The seals tested ranged from inexpensive low-tech seals to expensive high-tech seals. Many are currently used in critical applications. A total of 289 different attacks, at least one per seal, were devised and demonstrated. In many cases, simple changes to a seal and/or to how it is used can dramatically improve its effectiveness; however, these changes are almost never implemented. All of the seals tested were defeated quickly by using low-tech methods available to almost anyone. The cost of the seal did not correlate well with its effectiveness, and high-tech seals were not more difficult to defeat than many low-tech seals. This report concludes that tamper detection can and should be more effective, given its importance in providing protection for the users of the various items being sealed. Better seals, more optimal use protocols, additional research, greater awareness of seal vulnerabilities, more critical thinking, increased sophistication by seal users, and better tamper-detection training are sorely needed. Study limitations are noted. 30 references