The City Nature Challenge offers readers a fun and educational excuse to go outside and take pictures of their local flora and fauna for science (and to defend their city's honor). This annual citizen science project began in 2016 as a friendly rivalry between Los Angeles and San Francisco. Since then, it has grown into an international "bioblitz-style competition where cities are in a contest against each other to see who can make the most observations of nature, who can find the most species, and who can engage the most people." This year's City Nature Challenge takes place April 26 - April 29, 2019, with the results announced on May 5, 2019. Visitors to the site will find a map showing the numerous participating cities worldwide, as well as a list with links to each city's project website for further details. Educators at all levels may want to check out the Education Toolkit, which includes teaching resources organized by age group for learners from kindergarten to adults. No previous experience is required, and all that is needed to participate is a free iNaturalist account. Readers whose cities are not currently participating can sign up to start organizing for the next competition via a Google Forms link at the bottom.