In a lifelog, data from different digital sources are combined and processed to form a unified multimedia archive containing information about the quotidian activities of an individual. This dissertation aims to contribute to a responsible development of lifelog technology used by members of the general public for private reasons. Lifelog technology can benefit, but also harm lifeloggers and their social environment. The guiding idea behind this dissertation is that if the ethical challenges can be met and the opportunities realised, the conditions will be optimised for a responsible development and application of the technology. To achieve this, it is important to reflect on these concerns at an early stage of development before the existing rudimentary forms of lifelogs develop into more sophisticated devices with a broad societal application. For this research, a normative framework based on prima facie principles is used. Lifelog technology in its current form is a relatively novel invention and a consensus about its definition is still missing. Therefore the author aims to clarify the characteristics of lifelog technology. Next, the ethical challenges and opportunities of lifelogs are analysed, as they have been discussed in the scholarly literature on the ethics of lifelog technology. Against this backdrop, ethical challenges and opportunities are identified and elaborated. The normative analysis concentrates on two areas of concern, namely (1) the ethical challenges and opportunities that result from the use of lifelog technology, and (2) the conditions under which one becomes a lifelogger. For the first, three sets of key issues are discussed, namely issues to do with (a) privacy, (b) autonomy, and (c) beneficence. For the second, one key set of issues is examined, namely issues to do with autonomy. The discussion of each set of issues is concluded with recommendations designed to tackle the challenges and realise the opportunities.