1Place chicken thighs in 4- to 6-quart slow cooker; sprinkle with taco seasoning mix. Top with chiles and beans.
2Cover and cook on low heat setting 5 to 6 hours or until juice of chicken is no longer pink when the centers of the thickest pieces are cut.
3About 15 minutes before serving, heat taco shells as directed on package. Meanwhile, remove chicken from cooker; place on large plate. Shred chicken with 2 forks. Return chicken to bean mixture; mix well, mashing beans with fork.
4Serve chicken mixture with warm taco shells. Chicken mixture will hold on low heat setting up to 3 hours.