In looking at four broad factors related to teacher assignments in the Los Angeles School District--instructional load, homophily, colleague qualifications, and professional culture--researchers of urban education policy at the University of Southern California discovered three main lessons for practice: First, that teacher working conditions are complicated and can't always easily be summarized as "good" or "bad." Second, that "novice" teachers--which they define as teachers in their first five years in the classroom--often have the most challenging assignments. And finally, that education leaders need to find ways to improve working conditions for all teachers whenever possible.