How many times a week should you engage in weight training to build muscles?

There are a few answers here. With numerous professionals in the world, each have their different ideas of what a perfect schedule is.

With that said, there are two common and well-publicized workout schedules that have been proven to give results faster and more reliably than others.

The first and ultimately most effective is a workout that features strength training on Monday and Tuesday, cardio on Wednesday (running, using the elliptical, using the stairstepper, etc.), and strength training on Thursday and Friday. In this plan, the Monday and Thursday workouts promote building upper body muscles while Tuesday and Friday workouts promote lower body and core muscles. You have 2 days to rest so your body can recover between each workout, with a cardio day to burn off calories and maximize your workout in between each upper and lower body workout.

The second workout features an every other day strength building regimen. Monday, Wednesday, and Friday are workout days while Tuesday, Thursday, and Saturday are cardio days. Both the upper body and lower body (including the core) are worked out during the strength training days with the following day being a rest day to allow your body to recover.
I recommend that yo strength train no more than three times a week to avoid muscle damage, or what I have done is exercise one muscle group on day one and another on day two and rotate. Thus I can give each muscle group 24 hours to recover before using them again.

Here is an article that may be helpful and a link to a muscle building guru.That I like

Muscle Building Workouts - Build Muscle Fast With Only 2 Workouts a Week!

By Chess McDoogle

http://ezinearticles.com/?Muscle-Building-Workouts---Build-Muscle-Fast-With-Only-2-Workouts-a-Week!&id=3794494

http://tinyurl.com/ygv76e8
It often depends on your diet, and your willingness to lift. I lift 4 days a week, and focus on the "Big 3 Lifts" (Bench Press, Power Clean, and Squat), with multiple smalls lifts on the side. My entire goal at the start of my exercise plan was to build a lot of muscle, and it's working well.

Here's my schedule for the week on exercise:

MONDAY TUESDAY WEDNESDAY THURSDAY FRIDAY SATURDAY SUNDAY

(Lift) (Speed) (Lift) (Agility/ (Lift) (Lift/ speed) (rest)

endurance)

Also, diet well, drink a WHEY protein powder and/or a Creatine Supplement, get plenty of sleep, and overall just have fun. I hope this helped.
3 to 4 times a week
This actually depends on what your training goals are. However, a good target to aim for is ~3x per week. The following link provides a more indepth response to your question: http://total-fitness-guide.com/muscle_prog.php

AnswerBoth are correct. Work one set of muscles one day, let them rest and work another set of muscles the next. The idea is to exercise the muscles in an exhaustive workout then let them rest for a day and fully recover while you work out the other set. Some people pick upper body for one day and lower body for the next, but whatever works for you.

... that is completely utterly WRONG. You should workout everysingle muscle in your body in ONE day and let them rest for ONE week. No more, and no less