Literacy interventions in the family context have great potential to promote reading development in children. However, the results of meta-analyses indicate that family-based approaches tend not to be as effective as expected. Although the effectiveness of family literacy interventions can be assumed to hinge largely on the quality of their implementation in families, this aspect has attracted surprisingly little research attention to date. This article identifies, analyses, and discusses aspects of implementation quality that may enhance or diminish the effectiveness of family literacy interventions. Data from two evaluation studies of programmes for kindergarten- and school-age children were used to examine three types of implementation variables (intensity and quality of parent-child activities; support and training provided for parents; participation). The results indicate possibilities for how implementation quality in all three areas can be improved. Implications for future family literacy programmes as well as for evaluation and implementation studies are discussed.