Teaching expertise is characterized by effective strategies that engage students, convey content meaningfully, and evaluate student learning. One method that appears particularly effective when engaging students is the use of humor. Humor is a distinctly personal form of expression that others perceive to be funny or amusing. Positive, clever, or self-depreciating humor can invite students to engage. Conversely, negative humor, such as the use of sarcastic personal attacks, belittle students to control and manipulate. Differences between positive and negative humor can be found in the humorist’s intent and recipients’ perceptions. The purpose of this qualitative case study was to identify and analyze forms and effects of humor used by 2 award-winning physical educators in a large, suburban elementary school. Student in grades 1-5 attended class 5 times every 2 weeks for 50 min. I collected over 250 hours of ethnographic observation and interview data in 5 classes on one complete day each week during the 2001-02 school year. I interviewed teachers and 50 students selected to represent class demographics such as gender, ethnicity, skill level, body size, and enthusiasm. All interviews were recorded and transcribed. I analyzed data using comparative coding with a focus on emerging axial and selective thematic codes and triangulated data sources by participant (teacher, student), grade (1-5), and source (observation, interview). Member checks, peer reviews, and extended time in site enhanced trustworthiness. Results indicated that teachers’ used different forms of humor to gain student attention and assist students to focus and engage. Teachers consistently used positive humor from television commercials, puns and other word play, and self-depreciating comments. For example, teachers began one lesson by holding an imaginary phone and quietly repeating, “Can you here me now? …What about now? Can you hear me now?” as they moved around the class. They used homophones (words that sound the same, but are spelled differently) to engage students cognitively in exploring body actions and active word groups. Interviews revealed a planned and purposeful structure designed by teachers to relieve tension; both their own anxiousness about the lesson and students’ classroom-related stress. They used humor to emphasize particular content they intended students to remember and apply. Students acknowledged that these teachers were funny and realized that humor made the learning environment more relaxing and accessible to both skilled and unskilled students. Humor used within this positive environment appeared to be an effective tool to enhance student learning.