Young children ages 3 to 6 play a wide range of digital games, which are now available on large screens, handheld screens, electronic learning systems, and electronic toys, and their time spent with games is growing. This article examines effects of digital games and how they could be designed to best serve children's needs. A small body of research has found that games--when well designed--can provide rich, fun, interactive experiences that can foster young children's learning, cognitive development, skill building, social interactions, physical activity, and healthy behaviors. Research on games that are not well designed has found that violent content can lead to fear, hostility, desensitization, and aggressive behavior; stereotyped portrayals of characters can lead to stereotyped beliefs about others and oneself; and game playing can consume valuable time that could have been better spent in exploratory play, direct manipulation of objects in the environment, physical activity, and social interaction. More research is needed to discover the potential strengths and drawbacks of games for this age group to improve game design and guide decision-making about game purchases and implementation. Since young children are especially vulnerable to media messages, it is important that their media match their developmental needs, interests, and abilities. New data collection methods are enabling researchers to investigate children's responses to digital games with greater depth and accuracy and to discover how those responses are associated with outcomes. For example, software can record the time spent playing a game, time spent on specific game challenges, errors made, use of help and remediation, amount of exposure to educational content, and areas of success in the game. Data can also be collected with systems that record eye movements, technologies that recognize emotional responses to games by recording subtle shifts in facial expression, and functional magnetic resonance imaging of brain activity during game play, all of which can contribute to our understanding of processes and effects of young children's game playing. The results of research using these new methods and more traditional methods will help to discover principles of game design that can help make games more developmentally appropriate and beneficial, building on the ways young children naturally play and learn.