Clinical practice in the treatment of community-onset skin and soft tissue infections (SSTI) has not kept pace with the emergence of methicillin-resistant Staphylococcus aureus (MRSA) in the community. This clinical trial will evaluate clindamycin (CLINDA) and trimethoprim-sulfamethoxazole (TMP-SMX) and wound care for the outpatient management of uncomplicated skin and soft tissue infection (uSSTI) in 3 metropolitan areas, Chicago, Los Angeles, and San Francisco, cities with high prevalence of community acquired (CA)-MRSA. This is a phase IIb multicenter, stratified, randomized, double-blind trial in which enrolled subjects with abscess or cellulitis will be treated with CLINDA, TMP-SMX, or placebo. Participants will include 1310 non-immunocompromised out-patients age 6 months to 85 years with SSTIs not requiring hospital admission. Subjects will undergo a screening/baseline evaluation, including determination of presence and size of abscess and/or presence of cellulitis. Subjects will then be randomized to receive treatment with either CLINDA, TMP-SMX, or placebo depending on whether they have: a larger drainable abscess, defined as greater than 5 cm in diameter in adults and as greater than 3 cm in diameter for ages 6-11 months, greater than 4 cm for ages 1-8 years, and greater than 5 cm for age 9 years and older; a limited drainable abscess, defined as less than or equal to 5 cm for adults and as less than or equal to 3 cm for ages 6-11 months, less than or equal to 4 cm for ages 1-8 years, and less than or equal to 5 cm for age 9 years and older; or cellulitis or erysipelas only. If the diameter of the abscess greater than 5 cm (smaller for children depending on age) or 2 or more sites of skin infection are present the subject will be randomized (1:1) to 10 days of therapy with TMP-SMX or CLINDA. If the diameter of the abscess less than or equal to 5 cm (smaller for children depending on age) then the subject will be randomized (1:1:1) to TMP-SMX, CLINDA or placebo for 10 days. Subjects with cellulitis or erysipelas only will be randomized (1:1) to TMP-SMX or CLINDA for 10 days. Subjects will be provided study drug, instructed in its use, and scheduled for 4 follow-up visits including: wound check (24-48 hours after enrollment); end of therapy (48 hours after completion of therapy); test of cure (7-10 days after completion of therapy); and a final visit at one month after completion of therapy. The primary objectives of this study are: to compare the cure rate of CLINDA to that of TMP-SMX for the treatment of patients with cellulitis or larger abscess at the Test of Cure (TOC) visit and to compare the cure rate of CLINDA, TMP-SMX, and placebo, each in conjunction with surgical drainage for the treatment of subjects with limited abscess at the TOC visit.