Male or female subjects with mild to moderate plaque type psoriasis will present to the research center for evaluation for study entry. They will have been advised to present to the research center with clean skin and no topical products applied to the body, including medications, moisturizers, sunscreens, etc. If found to be suitable by meeting all inclusion criteria and none of the exclusion criteria, subjects will undergo selection of 2 target plaques by the dermatologist investigator. Each plaque will be graded for erythema, scaling, and induration. An Investigational Global Assessment (IGA) score will be assigned for each plaque. Plaques must have an IGA of mild (2) or moderate (3) to qualify for inclusion. The subjects will also assess each plaque for redness, thickness, and scaling. Each of the plaques will be photographed.The subjects will undergo D-squame tape strip removal of each of the 2 target psoriasis plaques. One plaque will serve as the tazarotene/halobetasol lotion treated plaque and the other will serve as the clobetasol propionate 0.05% cream treated plaque. 10 D-squames will be obtained with from each plaque. 5 tape strips will be placed in each glass jar. One jar will contain the even tape strips and the other jar will contain the odd tape strips. 10 D-squames will also be taken from normal skin to serve as a negative control in an individual without psoriasis. 5 tape strips will be placed in each glass jar. One jar will contain the even tape strips and the other jar will contain the odd tape strips. The D-squames will be frozen in a -80C freezer for later assessment. Five tape strips will be analyzed together to obtain adequate material for ELISA analysis. Two specimens jars will be prepared for from each of the 2 target plaques. One jar will be analyzed with the second jar serving as a back up.The subjects will have a number assigned to each of the treatment plaques. The numbers will be recorded on a body map. Two copies will be prepared. One copy will remain at the research center and the second copy will be provided to the subject. Each subject will receive one tube of tazarotene/halobetasol lotion for application to one randomized target plaque and a tube of clobetasol propionate 0.05% cream to apply the second randomized target plaque.Subjects will be provided with a diary. They will be instructed to apply the study product at bedtime to the designated target plaque. Care must be taken to apply the proper product to the proper plaque. Subjects will be instructed to return to the research center in 4 weeks. A reminder text for compliance will be provided prior to the week 4 visit.Subjects will return to the research center at week 4. The dermatologist investigator will evaluate each plaque for erythema, scaling, and induration. An Investigational Global Assessment (IGA) score will be assigned for each plaque. The subjects will also assess each plaque for redness, thickness, and scaling. Each of the plaques will be photographed. The subjects will undergo D-squame tape strip removal of 10 tape strips for each of the 2 target psoriasis plaques. Five tape strips will be placed in each jar with one jar receiving the even tape strips and the other jar receiving the odd tape strips. The D-squames will be frozen in a -80C freezer for later assessment. Subjects will discontinue treatment of the plaques at this time. All medication and study diaries will be collected. Subjects will be asked to return to the research center at week 8. A reminder text for compliance will be sent prior to the week 8 visit.Subjects will return to the research center at week 8. No treatment will be applied to the target plaques for the past 4 weeks. The dermatologist investigator will evaluate each plaque for erythema, scaling, and induration. An Investigational Global Assessment (IGA) score will be assigned for each plaque. The subjects will also assess each plaque for redness, thickness, and scaling. Each of the plaques will be photographed. The subjects will undergo D-squame tape strip removal 10 times for each of the 2 target psoriasis plaques. Five tape strips will be placed in each jar with one jar containing the even tape strips and the other jar containing the odd tape strips. The D-squames will be frozen in a -80C freezer for later assessment. Subjects will complete their study participation at this time.The D-squames will be analyzed using ELISA for the amount of TNF-a and IL-17A present after 4 weeks of treatment with tazarotene/halobetasol lotion to one randomized target plaque and clobetasol propionate 0.05% cream to apply the second randomized target plaque. Treatment will be discontinued at week 4 and subjects will remain untreated for the subsequent 4 weeks. At week 8, D-squames will be analyzed using ELISA for the amount of TNF-a and IL-17A present after 4 weeks off treatment with tazarotene/halobetasol lotion to one randomized target plaque and clobetasol propionate 0.05% cream to apply the second randomized target plaque. This research will allow comparison between a retinoid/topical corticosteroid combination and a topical corticosteroid alone in terms of inflammatory mediator reduction. It will also provide insight into the ability of a retinoid/topical corticosteroid combination to produce longer lasting inflammatory mediator reduction than a topical corticosteroid alone.