Yoga practice is known to improve well-being and decrease stress. However, acute yoga is understudied. This study investigated the effects of two different types of yoga on affect and salivary cortisol levels in college women. Thirty-three women aged 18-30 years each completed 1-hour sessions of power yoga and stretch yoga. Measures of affect and salivary cortisol were assessed before, during, and after each session. Participants perceived power yoga to be more pleasurable and energizing. Salivary cortisol significantly decreased after both yoga sessions. Thus, even one session of yoga may be effective in improving affect and decreasing stress in college women.