The purpose of this study is to determine whether the combinational use of ammonium lactate lotion 12% (Lac-Hydrin) and halobetasol propionate ointment 0.05% (Ultravate) is safe and effective in the initial treatment and long-term maintenance of psoriasis. Patients will use both medications continuously for two weeks and those who obtain a good improvement based on investigator clinical assessments will be randomized to Lac-Hydrin lotion twice daily every day with placebo ointment or Ultravate ointment twice daily on weekends only for up to 24 more weeks.