The Self-Administered Interview© (SAI©) is an eyewitness interviewing tool designed to help protect eyewitness memory and elicit a comprehensive initial statement (Gabbert, Hope, & Fisher, 2009). Early research shows promising results in general adult samples. Whether the SAI© is an effective tool for older adult witnesses has not yet been fully addressed. Older adults will become increasingly important as a witness population in the future, yet perform worse compared to young adults. Some attempts have been made to aid older adult witnesses, but an easy-to-apply and effective method is yet to be introduced. This dissertation presents an overview of current knowledge on eyewitnesses and provides a theoretical basis for the empirical chapters. It further presents results of a systematic review and several meta-analyses on the effectiveness of the SAI© as a means to enhance eyewitness testimony. The meta-analyses cover 38 experimental comparisons from 22 empirical studies representing 1712 interviewees. Results indicate a strong benefit of the SAI both immediately after the witnessed crime (d = 1.20) and in a delayed recall (d = 0.92 compared to no initial recall) after one to three weeks. The third large chapter of this dissertation presents the results of an experiment that investigated the effectiveness of the SAI© for older witnesses’ testimony, suggestibility and lineup performance. 144 participants, half of which were 60 years or older and half aged 18-30 years, took part in two sessions. In the first session, they were shown a film of a staged crime and either filled in the SAI©, gave a written free recall or no initial recall. In the second session after one week they were then asked to give a free recall of what they remembered, answer questions including suggestive questions, and also to identify the perpetrator from the film from a 6-person simultaneous photo lineup. Results confirm the classic SAI© effect for young adults, show a small beneficial effect for older adults and also indicate a beneficial effect for lineup performance for the first time.